Light propagation characteristic control apparatus, optical display apparatus, light propagation characteristic control program, optical display apparatus control program, light propagation characteristic control method and optical display apparatus control method

ABSTRACT

Exemplary embodiments of the present invention provide a light propagation characteristic control apparatus which extends the light-intensity dynamic range and the number of levels, and are suited for enhancing image quality and reducing the size and generation time of tables. Exemplary embodiments provide a projection display apparatus that tentatively decides a transmissivity T 2  of each pixel of a color-modulation light valve depending upon HDR display data, and decides a transmissivity T 1  of each pixel of an intensity-modulation light valve depending upon a tentatively decided transmissivity T 2  and the HDR display data, and a control value of each pixel of the intensity-modulation light valve depending upon a decided transmissivity T 1 . Depending upon a decided transmissivity T 1  and the HDR display data, transmissivity T 2  is decided of each pixel of the color-modulation light valve. Depending upon a decided transmissivity T 2 , a control value is decided of each pixel of the color-modulation light valve.

BACKGROUND

Exemplary embodiments of the present invention relate to an apparatus,program and method to control the light propagation characteristic of anoptical system to modulate the light from a light source through aplurality of light modulator elements. Exemplary embodiments furtherprovide a light propagation characteristic control apparatus, opticaldisplay apparatus, light propagation characteristic control program,optical display apparatus control program, light propagationcharacteristic control method and optical display apparatus controlmethod which extends the light-intensity dynamic range and the number oflevels, and are suited to improve image quality and reduce the size andgeneration time of tables.

The enhancement of image quality is remarkable in the optical displays,such as LCDs (liquid crystal displays), ELs, plasma displays, CRTs(cathode ray tubes) and projectors, thus realizing the performance ofresolution and color gamut nearly matched to human visualcharacteristics. However, as for light-intensity dynamic range, thereproduction scope lies nearly 1-10² [nit] at most while the number oflevels generally is 8 bits. Meanwhile, the human sense of sight has alight-intensity dynamic range of nearly 10⁻²-10⁴ [nit] at one time ofvisual perception and an intensity discrimination ability of around 0.2[nit]. This, if converted into the number of levels, is consideredequivalent to 12 bits. When viewing a display image on the existingoptical display through the visual characteristic like this,light-intensity dynamic range looks conspicuously narrow. In addition,display image is perceivably insufficient in reality and impressions dueto the shortage of intensity levels in the shadow or highlight areas.

In computer graphics (hereinafter, abbreviated as CG) for use in movies,games, etc., the movement is toward pursuing a reality of expression byproviding display data (hereinafter, HDR (high dynamic range) displaydata) with a light-intensity dynamic range and the number of levelsclosely approximated to the human sense of sight. However, because ofinsufficient performance of the optical display to display the same,there is a problem the power of expression the CG content possessed innature could not be exhibited to a full extent.

Furthermore, the next-generation OS (operating system) is scheduled toadopt a 16-bit color space. This drastically increases thelight-intensity dynamic range and intensity levels as compared to thecurrent 8-bit color space. Therefore, there is a desire for realizing anoptical display capable of making use of the 16-bit color space.

Of the optical displays, the projection displays, such as liquid-crystalprojectors and DLP projectors, are capable of making a large-screendisplay. Thus, those are apparatuses effective reproducing reality andexpressions in the display image. In this field, the following proposalhas been made in order to address or solve the above discussed and/orother problems.

Related art document JP-A-2001-100689 discloses a technology of a highdynamic range of projection display that has a light source, a firstlight modulator element to modulate the intensity of light over theentire wavelength region, and a second light modulator element tomodulate the light intensity in the wavelength regions as to therespective wavelength regions of RGB three primary colors in thewavelength regions of light. The light from the light source ismodulated by the first light modulator element to form a desired lightintensity distribution, whose optical image is focused to andcolor-modulated on a pixel plane of the second light modulator elementthereby projecting the light secondary-modulated. The first lightmodulator element and the second light modulator element have respectivepixels under separate control on the basis of the first and secondcontrol values decided from the HDR display data. The light modulatorelement has a pixel or segment structure where transmissivity is underindependent control, using a transmissivity modulation element capableof controlling two-dimensional transmissivity distribution. Therepresentative examples include a liquid-crystal light valve. Meanwhile,a reflectivity modulation element may be used in place of thetransmissivity modulation element, the representative examples of whichinclude a DMD.

Now consider a case of using a light modulator element having atransmissivity of 0.2% in dark display and of 60% in light display. Thelight modulator element singly is given a light-intensity dynamic rangeof 60/0.2=300. The related art document JP-A-2001-100689 discloses aprojection display capable of realizing a light-intensity dynamic rangeof 300×300=90000 because its light-intensity dynamic range correspondingto an arrangement of light modulator elements having a light-intensitydynamic range of 300 optically in series. Meanwhile, this concept isequivalently true for the number of levels, i.e. the 8-bit-leveledoptical modulator elements optically arranged in series provide thenumber of levels exceeding 8 bits.

Related art document Helge Seetzen, Lome A. Whitehead, Greg Ward, “AHigh Dynamic Range Display Using Low and High Resolution Modulators”,SID Symposium 2003, pp.1450-1453 (2003) (hereinafter Seetzen) disclosesprojection displays realizing high light-intensity dynamic range and adisplay as disclosed in related art document JP-A-2002-99250. Bothrelated art documents use an LCD as a first light modulator element anda modulatable lighting, such as an LED or a fluorescent lamp, as asecond light modulator element.

SUMMARY

HDR display data is image data capable of realizing a highlight-intensity dynamic range not to be realized on the related artimage format such as sRGB. This stores pixel values representative ofintensity levels, on all the pixels of the image. Assuming that thepixel p of the HDR display data has an intensity level Rp, the pixel ofthe first light modulator element corresponding to the pixel p has atransmissivity T1 and the pixel of the second light modulator elementcorresponding to the pixel p has a transmissivity T2, the followingequations (1) and (2) are held.Rp=Tp×Rs   (1)Tp=T 1×T 2×G   (2)where, in equations (1) and (2), Rs is an intensity level of the lightsource and G is a gain, each of which is a constant. Meanwhile, Tp is alight modulation ratio.

It can be seen, from equations (1) and (2) that there are an uncountablenumber of combinations of T1 and T2 as to the pixel p. However, T1 andT2 are not allowed to be arbitrarily decided. Because image quality willdeteriorate by a certain manner of decision, there is a need to properlydecide T1 and T2 in consideration of image quality.

The invention described in Seetzen is nothing more than a conceptionalexplanation on the fact that high light-intensity dynamic range is to berealized when using the two light modulator elements. It does not reacha disclosure on how the control value of each pixel of the first andsecond light modulator elements (i.e. T1 and T2) is decided dependingupon HDR display data. Accordingly, there is a problem that imagequality will be deteriorated by a certain manner of deciding T1 and T2.

Meanwhile, in the invention described in JP-A-2002-99250,intensity-level tables are held in the number corresponding to thenumber of levels of the backlight. Thus, there is a problem that, whenthe number of levels of the backlight are increased, there is anincrease of the size of intensity level table and the time required togenerate intensity level tables.

Therefore, exemplary embodiments of the present invention have been madeto address the above discussed and/or other problems involved in therelated arts. Exemplary embodiments provide a light propagationcharacteristic control apparatus, optical display apparatus, lightpropagation characteristic control program, optical display apparatuscontrol program, light propagation characteristic control method andoptical display apparatus control method which will realize theextension of light-intensity dynamic range and the number of levels andis suited to improve image quality and reduce the size and generationtime of tables.

[Exemplary Embodiment 1]

In order to address or solve the above discussed and/or other problems,a light propagation characteristic control apparatus of exemplaryembodiment 1 is an apparatus to be applied to an optical system tomodulate light from a light source through a first light modulatorelement having a plurality of pixels capable of independentlycontrolling light propagation characteristics and a second lightmodulator element having a plurality of pixels capable of independentlycontrolling light propagation characteristics, the apparatus including:

-   -   a light propagation characteristic tentative deciding device to        tentatively decide a light propagation characteristic of each        pixel of the second light modulator element depending upon        display data; and    -   a first light propagation characteristic deciding device to        decide a light propagation characteristic of each pixel of the        first light modulator element depending upon a light propagation        characteristic tentatively decided by the light propagation        characteristic tentative deciding device and the display data;    -   the light propagation characteristic tentative deciding device        being allowed to tentatively decide a light propagation        characteristic of each pixel of the second light modulator        element by use of a gamma characteristic expression to calculate        an intensity level of light to be modulated through the first        and second light modulator elements depending upon an intensity        level of light to be modulated through the second light        modulator element and a gamma coefficient.

With this structure, the light propagation characteristic tentativedeciding device tentatively decides a light propagation characteristicof each pixel of the second light modulator element by use of a gammacharacteristic expression depending upon display data while the firstlight propagation characteristic deciding device decides a lightpropagation characteristic of each pixel of the first light modulatorelement depending upon a tentatively decided light propagationcharacteristic and the display data.

Because the light from the light source is modulated through the firstand second light modulator elements, it is possible to obtain an effectof realizing a comparatively high intensity dynamic range and the numberof levels. Meanwhile, because the light propagation characteristic ofeach pixel of the second light modulator element is determined by thegamma characteristic expression, it is possible to obtain an effect ofobtaining an image reduced in intensity and color irregularities and toreduce the possibility of deteriorated image quality as compared to therelated art. Furthermore, it is possible to obtain an effect that thelight propagation characteristic of each pixel of the second lightmodulator element can be determined comparatively rapidly because ofcomparatively simple operation of the gamma characteristic expression.Furthermore, it is not necessary to hold intensity tables in the numbercorresponding to the number of levels, there is little increase in thesize and generation time of an intensity table as compared to therelated art even where increasing the number of levels.

Here, light propagation characteristic refers to a characteristic havingan effect upon light propagation, which includes light transmissivity,reflectivity, refractivity and other propagation characteristics. In thefollowing, this is true for the optical display apparatus of exemplaryembodiment 2, the light propagation characteristic control program ofexemplary embodiment 11, the optical display apparatus control programof exemplary embodiment 12, the light propagation characteristic controlmethod of exemplary embodiment 21 and the optical display apparatuscontrol method of exemplary embodiment 22.

Meanwhile, the light source can use anything provided that it is amedium for generating light, e.g. a light source incorporated in anoptical system such as a lamp or an exterior light source such as thesun or a room light. In the following, this is true for the lightpropagation characteristic control program of exemplary embodiment 11and the light propagation characteristic control method of exemplaryembodiment 21.

Meanwhile, the intensity of light may be given an index by physicalradiance (W/(sr·m²)) not taking into account human visual characteristicor by luminance (cd/m²) taking into account human visual characteristic.In the following, this is true for the optical display apparatus ofexemplary embodiment 2, the light propagation characteristic controlprogram of exemplary embodiment 11, the optical display apparatuscontrol program of exemplary embodiment 12, the light propagationcharacteristic control method of exemplary embodiment 21 and the opticaldisplay apparatus control method of exemplary embodiment 22.

[Exemplary Embodiment 2]

Meanwhile, in order to address or achieve the above object, an opticaldisplay apparatus of exemplary embodiment 2 is an apparatus having alight source, a first light modulator element having a plurality ofpixels capable of independently controlling light propagationcharacteristics and a second light modulator element having a pluralityof pixels capable of independently controlling light propagationcharacteristics, to thereby modulate light from the light source throughthe first and second light modulator elements and display an image, theapparatus includes:

-   -   a light propagation characteristic tentative deciding device to        tentatively decide a light propagation characteristic of each        pixel of the second light modulator element depending upon        display data;    -   a first light propagation characteristic deciding device to        decide a light propagation characteristic of each pixel of the        first light modulator element depending upon the light        propagation characteristic tentatively decided by the light        propagation characteristic tentative deciding device and the        display data;    -   a first control value deciding device to decide a control value        of each pixel of the first light modulator element depending        upon the light propagation characteristic decided by the first        light propagation characteristic deciding device;    -   a second light propagation characteristic deciding device to        decide a light propagation characteristic of each pixel of the        second light modulator element depending upon the light        propagation characteristic decided by the first light        propagation characteristic deciding device and the display data;        and    -   a second control value deciding device to decide a control value        of each pixel of the second light modulator element depending        upon the light propagation characteristic decided by the second        light propagation characteristic deciding device;    -   the light propagation characteristic tentative deciding device        being allowed to tentatively decide a light propagation        characteristic of each pixel of the second light modulator        element by use of a gamma characteristic expression to calculate        an intensity level of light to be modulated through the first        and second light modulator elements depending upon an intensity        level of light to be modulated through the second light        modulator element and a gamma coefficient.

With this structure, the light propagation characteristic tentativelydeciding device tentatively decides a light propagation characteristicof each pixel of the second light modulator element by use of the gammacharacteristic expression depending upon display data. Then, the firstlight propagation characteristic deciding device decides a lightpropagation characteristic of each pixel of the first light modulatorelement depending upon the tentatively decided light propagationcharacteristic of the second light modulator element and display datawhile the first control-value deciding device decides a control value ofeach pixel of the first light modulator element depending upon thedecided light propagation characteristic of the first light modulatorelement. Then, the second light propagation characteristic decidingdevice decides a light propagation characteristic of each pixel of thesecond light modulator element depending upon the decided lightpropagation characteristic of the first light modulator element anddisplay data while the second control-value deciding device decides acontrol value of each pixel of the second light modulator elementdepending upon the decided light propagation characteristic of thesecond light modulator element.

Due to this, because the light from the light source is modulatedthrough the first and second light modulator elements, it is possible toobtain an effect of realizing a comparatively high light-intensitydynamic range and the number of levels. Meanwhile, because the lightpropagation characteristic of each pixel of the second light modulatorelements is determined by the gamma characteristic expression, it ispossible to obtain an effect of obtaining an image reduced in luminanceand color irregularities and to reduce the possibility of a deterioratedimage quality as compared to the related art. Furthermore, it ispossible to obtain an effect that the light propagation characteristicof each pixel of the second light modulator element can be determinedcomparatively rapidly because of comparatively simple operation of thegamma characteristic expression. Furthermore, because of no need to holdintensity level tables in the number corresponding to the number oflevels, it is possible to obtain an effect that, there is littleincrease in the size and generation time of an intensity level table ascompared to the related art even where the number of levels isincreased.

Here, the second light propagation characteristic deciding device may beof any structure provided that the light propagation characteristic ofeach pixel of the second light modulator element is to be decideddepending upon the light propagation characteristic decided by the firstlight propagation characteristic deciding device and display data. Itmay be made to decide a light propagation characteristic of each pixelof the second light modulator element depends upon an operation resultor conversion result of an operation or conversion carried out dependingupon a light propagation characteristic decided by the first lightpropagation characteristic deciding device without being limited to thelight propagation characteristic decided by the first light propagationcharacteristic decided by the first light propagation characteristicdeciding device. For example, because the control value decided by thefirst control-value deciding device is decided depending upon the lightpropagation characteristic decided by the first light propagationcharacteristic deciding device, the second light propagationcharacteristic deciding device is allowed to decide a light propagationcharacteristic of each pixel of the second light modulator elementdepending upon the control value decided by the first control-valuedeciding device and display data. In the following, this is true for theoptical display apparatus control program of exemplary embodiment 12.

[Exemplary Embodiment 3]

Furthermore, an optical display apparatus of exemplary embodiment 3 isaccording to an optical display apparatus of exemplary embodiment 2. Thelight propagation characteristic tentative deciding device calculatesthe intensity level n with use of the following gamma characteristicexpression by taking as Rp an intensity level of a pixel p in thedisplay data, as Rmax a maximum value of intensity level in the displaydata, as n an intensity level of a pixel of second light modulatorelement corresponding to the pixel p, as m a coefficient in accordancewith the number of levels of the second light modulator element and as γa gamma coefficient,Rp=Rmax×(n/m)^(γ)and tentatively decides a light propagation characteristic of the pixelof second light modulator element corresponding to the pixel p based onthe calculated intensity level n.

With this structure, the light propagation characteristic tentativedeciding device calculates the intensity level n of the pixel of secondlight modulator element corresponding to the pixel p, by use of a gammacharacteristic expression. Depending upon a calculated intensity leveln, tentatively decided is a light propagation characteristic of thepixel of second light modulator element corresponding to the pixel p.

This can obtain an image reduced in luminance and color irregularities.Accordingly, it is possible to further reduce the possibility of adeteriorated image quality. Meanwhile, because a comparatively suitableintensity level n can be determined by one operation, there is no needfor a feedback process. Thus, it is possible to obtain an effect ofbeing suited for motion-picture processing.

[Exemplary Embodiment 4]

Furthermore, an optical display apparatus of exemplary embodiment 4 isaccording to an optical display apparatus of exemplary embodiment 3. Thecoefficient m is set at a value obtained by multiplying a multipliergreater than 1 to the number of levels of the second light modulatorelement.

With this structure, it is possible to precisely reproduce a darkintensity level of an image to be formed by the second light modulatorelement as compared to the case of setting the coefficient m at thenumber of levels of the second light modulator element, thus obtainingan effect to further reduce the possibility to deteriorate imagequality.

[Exemplary Embodiment 5]

Furthermore, an optical display apparatus of exemplary embodiment 5 isaccording to any of optical display apparatuses of exemplary embodiments3 and 4, the gamma coefficient γ being set at 4 or greater.

With this structure, it is possible to precisely reproduce a darkintensity level of an image to be formed by the second light modulatorelement as compared to the case of setting the gamma coefficient γ atless than 4.

[Exemplary Embodiment 6]

Furthermore, an optical display apparatus of exemplary embodiment 6 isaccording to any of optical display apparatuses of exemplary embodiments3 and 4, the gamma coefficient γ being set at 0 or greater and ¼ orsmaller.

With this structure, it is possible to precisely reproduce a lightintensity level of an image to be formed by the second light modulatorelement as compared to the case of setting the gamma coefficient γ at anegative value or a value greater than ¼.

The present inventors have eagerly made studies and found that imagedeterioration depends upon how to determine T1 and T2, furthermore,under the influence of the following factor.

Where the first light modulator element and the second light modulatorelement respectively have different resolutions, there is a possibilitythat, concerning one pixel p1 of the first light modulator element, thepixel p1 overlaps, on an optical path, with a plurality of pixels of thesecond light modulator element. Conversely, concerning one pixel p2 ofthe second light modulator element, the pixel p2 overlaps, on an opticalpath, with a plurality of pixels of the first light modulator element.Here, in the case to calculate a transmissivity T1 for the pixel p1 ofthe first light modulator element, it can be considered that, if thetransmissivities T2 of a plurality of overlapping pixels of the secondlight modulator element, a mean value, etc. of the transmissivities T2is calculated so that the calculated mean value, etc. is regarded as atransmissivity T2 of the pixel of second light modulator elementcorresponding to the pixel p1 thereby calculating a transmissivity T1 byuse of equations (1) and (2). However, the mean value, etc. is nothingmore than being regarded as a transmissivity T2 of the second lightmodulator element, errors inevitably occur. Such errors occur regardlessof the order of decision, i.e. in the case of deciding a transmissivityT1 of the first light modulator element first and in the case ofdeciding a transmissivity T2 of the second light modulator elementfirst. For the one to decide a display resolution of the first andsecond light modulator elements, it is preferred to reduce the error toa possible small extent because of its significant visual influence.

For this reason, consideration is made as to how the magnitude of errorchanges with a change of decision order. At first, consider a case ofdeciding a transmissivity T2 of the second light modulator elementfirst. The transmissivity T1 of the pixel p1 of the first lightmodulator element can be calculated by calculating a mean value, etc. ofthe transmissivities T2 of a plurality of overlapping pixels of thesecond light modulator element and then by the foregoing equations (1)and (2) on the basis of the calculated mean value, etc. and HDR displaydata. As a result, as considered from the pixel p1 of the first lightmodulator element, the transmissivity T1 has an error occurring relativeto the transmissivities T2 of the plurality of overlapping pixels of thesecond light modulator element. The error is in a degree of an errorcaused in the statistic operation of a mean value, etc. Contrary tothis, as considered from the pixel p2 of the second light modulatorelement, the transmissivity T2, even if calculating a mean value, etc.of the transmissivities T1 of the plurality of overlapping pixels of thefirst light modulator element, possibly has such a great error relativeto the mean value, etc. as not to satisfy the foregoing equations (1)and (2). This can be considered responsible for the following, i.e. evenwhen defining a relationship with a plurality of overlapping pixels ofthe second light modulator element with reference to the pixel p1(relationship satisfying equations (1) and (2)), the relationship inreverse is not necessarily held true. Accordingly, error is possiblygreater in the transmissivity T2 of the second light modulation element.

Accordingly, when deciding the transmissivity T1 of the first lightmodulator element first, error is possibly greater in the transmissivityT1 of the first light modulator element.

From the above, a conclusion is obtained that the influence of error canbe reduced if deciding later a transmissivity of the first and secondlight modulator elements decisive of the resolution of display, from theviewpoint of enhancing image quality.

[Exemplary Embodiment 7]

Furthermore, an optical display apparatus of exemplary embodiment 7 isaccording to any of optical display apparatuses of exemplary embodiments2 to 6, the second light modulator element being a light modulatorelement decisive of a resolution of display.

With this structure, because decided later is a light propagationcharacteristic of the second light modulator elements decisive of theresolution of display, it is possible to obtain an effect of suppressingthe influence of error and further reducing the possibility ofdeteriorated image quality.

[Exemplary Embodiment 8]

Furthermore, an optical display apparatus of exemplary embodiment 8 isaccording to any of optical display apparatuses of exemplary embodiments2 to 7. One of the first and second light modulator elements is aparticular-wavelength-regioned intensity modulator element to modulatean intensity of light in a particular wavelength region as to aplurality of different particular wavelength regions of a wavelengthregion of light. The other of the first and second light modulatorelements being the entire-wavelength-regioned modulator element tomodulate an intensity of light over the entire wavelength region.

With this structure, one of the first and second light modulatorelements modulates an intensity of light at the particular wavelengthregion while the other of the first and second light modulator elementsmodulates an intensity of light over the entire wavelength region oflight.

Due to this, because it is satisfactory to merely add one lightmodulator element to the related art optical display apparatus, it ispossible to obtain an effect that the optical display apparatus ofexemplary embodiments of the invention can be structured comparativelyeasily.

Here, the particular-wavelength-regioned intensity modulator element maybe in any structure provided that to modulate an intensity of light in aparticular wavelength region as to a plurality of different particularwavelength regions of a wavelength region of light, i.e. may bestructured by a single particular-wavelength-regioned intensitymodulator element or by a plurality of particular-wavelength-regionedintensity modulator elements. In the former case, the representativeexample includes a structure of a liquid-crystal light valve providedwith an RGB-three-primary-colored color filter. Meanwhile, in the lattercase, for each particular wavelength region, it is satisfactory toprovide a particular-wavelength-regioned intensity modulator element tomodulate an intensity of light over the particular wavelength region.The representative example includes a structure including aliquid-crystal light valve based on RGB three primary colors. In thefollowing, this is true for the optical display apparatus of exemplaryembodiment 9, the optical display apparatus control program of exemplaryembodiments 18 and 19, and the optical display apparatus control methodof exemplary embodiments 28 and 29.

Meanwhile, the particular wavelength region can be arbitrarily setwithout limited to the setting based on RGB three primary colors.Nevertheless, the setting based on RGB three primary colors makes itpossible to utilize the existing liquid-crystal light valve withoutchange, which is advantageous in terms of cost. In the following, thisis true for the optical display apparatus of exemplary embodiment 9, theoptical display apparatus control program of exemplary embodiments 18and 19, and the optical display apparatus control method of exemplaryembodiments 28 and 29.

[Exemplary Embodiment 9]

Furthermore, an optical display apparatus of exemplary embodiment 9 isaccording to any of optical display apparatuses of exemplary embodiments2 to 7. The first and second light modulator elements areparticular-wavelength-regioned intensity modulator elements to modulatean intensity of light in a particular wavelength region as to aplurality of different particular wavelength regions of a wavelengthregion of light.

With this structure, the first and second light modulator elementsmodulate an intensity of light at the particular wavelength region bytwo stages.

Due to this, because the intensity of light at a particular wavelengthregion of light can be modulated independently in two stages, it ispossible to obtain an effect of further reducing the possibility ofdeteriorated image quality.

[Exemplary Embodiment 10]

Furthermore, an optical display apparatus according to any of opticaldisplay apparatuses of exemplary embodiments 2 to 9, the second lightmodulator element having a higher resolution than the first lightmodulator element.

With this structure, because the second light modulator element providesthe greater visual influence, the effect of error can be suppressedfurthermore. Hence, it is possible to obtain an effect of furtherreducing the possibility of deteriorated image quality.

[Exemplary Embodiment 11]

Meanwhile, in order to address or achieve the above object, a lightpropagation characteristic control program of exemplary embodiment 11 isa program to be applied to an optical system to modulate light from alight source through a first light modulator element having a pluralityof pixels capable of independently controlling light propagationcharacteristics and a second light modulator element having a pluralityof pixels capable of independently controlling light propagationcharacteristics. The program causes a computer to execute a process tobe realized as a light propagation characteristic tentative decidingdevice to tentatively decide a light propagation characteristic of eachpixel of the second light modulator element depending upon display data;and

-   -   a first light propagation characteristic deciding device to        decide a light propagation characteristic of each pixel of the        first light modulator element depending upon a light propagation        characteristic tentatively decided by the light propagation        characteristic tentative deciding device and the display data.

The light propagation characteristic tentative deciding device isallowed to tentatively decide a light propagation characteristic of eachpixel of the second light modulator element by use of a gammacharacteristic expression to calculate an intensity level of light to bemodulated through the first and second light modulator elementsdepending upon an intensity level of light to be modulated through thesecond light modulator element and a gamma coefficient.

With this structure, in the case the program is read out by the computerand then the computer executes the process according to the program readout, it is possible to obtain the operation and effect equivalent tothat of the light propagation characteristic control apparatus ofexemplary embodiment 1.

[Exemplary Embodiment 12]

Meanwhile, in order to address or achieve the above object, a lightdisplay apparatus control program of exemplary embodiment 12 is aprogram to control an optical display apparatus having a light source, afirst light modulator element having a plurality of pixels capable ofindependently controlling light propagation characteristics and a secondlight modulator element having a plurality of pixels capable ofindependently controlling light propagation characteristics, to therebymodulate light from the light source through the first and second lightmodulator elements and display an image.

The program causes a computer to execute a process to be realized as alight propagation characteristic tentative deciding device totentatively decide a light propagation characteristic of each pixel ofthe second light modulator element depending upon display data;

-   -   a first light propagation characteristic deciding device to        decide a light propagation characteristic of each pixel of the        first light modulator element depending upon the light        propagation characteristic tentatively decided by the light        propagation characteristic tentative deciding device and the        display data;    -   a first control value deciding device to decide a control value        of each pixel of the first light modulator element depending        upon the light propagation characteristic decided by the first        light propagation characteristic deciding device;    -   a second light propagation characteristic deciding device to        decide a light propagation characteristic of each pixel of the        second light modulator element depending upon the light        propagation characteristic decided by the first light        propagation characteristic deciding device and the display data;        and    -   a second control value deciding device to decide a control value        of each pixel of the second light modulator element depending        upon the light propagation characteristic decided by the second        light propagation characteristic deciding device.

The light propagation characteristic tentative deciding device isallowed to tentatively decide a light propagation characteristic of eachpixel of the second light modulator element by use of a gammacharacteristic expression to calculate an intensity level of light to bemodulated through the first and second light modulator elementsdepending upon an intensity level of light to be modulated through thesecond light modulator element and a gamma coefficient.

With this structure, in the case the program is read out by the computerand then the computer executes the process according to the program readout, it is possible to obtain the operation and effect equivalent tothat of the optical display apparatus of exemplary embodiment 2.

[Exemplary Embodiment 13]

Furthermore, an optical display apparatus control program of exemplaryembodiment 13 is according to an optical display apparatus controlprogram of exemplary embodiment 12. The light propagation characteristictentative deciding device calculates the intensity level n with use ofthe following gamma characteristic expression by taking as Rp anintensity level of a pixel p in the display data, as Rmax a maximumvalue of intensity level in the display data, as n an intensity level ofa pixel of second light modulator element corresponding to the pixel p,as m a coefficient in accordance with the number of levels of the secondlight modulator element and as γ a gamma coefficient,Rp=Rmax×(n/m)^(γ)and tentatively decides a light propagation characteristic of the pixelof second light modulator element corresponding to the pixel p based onthe calculated intensity level n.

With this structure, in the case the program is read out by the computerand then the computer executes the process according to the program readout, it is possible to obtain the operation and effect equivalent tothat of the optical display apparatus of exemplary embodiment 3.

[Exemplary Embodiment 14]

Furthermore, an optical display apparatus control program of exemplaryembodiment 14 is according to an optical display apparatus controlprogram of exemplary embodiment 13. The coefficient m is set at a valueobtained by multiplying a multiplier greater than 1 to the number oflevels of the second light modulator element.

With this structure, in the case the program is read out by the computerand then the computer executes the process according to the program readout, it is possible to obtain the operation and effect equivalent tothat of the optical display apparatus of exemplary embodiment 4.

[Exemplary Embodiment 15]

Furthermore, an optical display apparatus control program of exemplaryembodiment 15 is according to any of optical display apparatus controlprograms of exemplary embodiments 13 and 14, the gamma coefficient γbeing set at 4 or greater.

With this structure, in the case the program is read out by the computerand then the computer executes the process according to the program readout, it is possible to obtain the operation and effect equivalent tothat of the optical display apparatus of exemplary embodiment 5.

[Exemplary Embodiment 16]

Furthermore, an optical display apparatus control program of exemplaryembodiment 16 is according to any of optical display apparatus controlprograms of exemplary embodiments 13 and 14, the gamma coefficient γbeing set at 0 or greater and ¼ or smaller.

With this structure, in the case the program is read out by the computerand then the computer executes the process according to the program readout, it is possible to obtain the operation and effect equivalent tothat of the optical display apparatus of exemplary embodiment 6.

[Exemplary Embodiment 17]

Furthermore, an optical display apparatus control program of exemplaryembodiment 17 is according to any of optical display apparatus controlprograms of exemplary embodiments 12 to 16, the second light modulatorelement being a light modulator element decisive of a resolution ofdisplay.

With this structure, in the case the program is read out by the computerand then the computer executes the process according to the program readout, it is possible to obtain the operation and effect equivalent tothat of the optical display apparatus of exemplary embodiment 7.

[Exemplary Embodiment 18]

Furthermore, an optical display apparatus control program of exemplaryembodiment 18 is according to any of optical display apparatus controlprograms of exemplary embodiments 12 to 17. One of the first and secondlight modulator elements is a particular-wavelength-regioned intensitymodulator element to modulate an intensity of light in a particularwavelength region as to a plurality of different particular wavelengthregions of a wavelength region of light. The other of the first andsecond light modulator elements are an entire-wavelength-regionedmodulator element to modulate an intensity of light over the entirewavelength region.

With this structure, in the case the program is read out by the computerand then the computer executes the process according to the program readout, it is possible to obtain the operation and effect equivalent tothat of the optical display apparatus of exemplary embodiment 8.

[Exemplary Embodiment 19]

Furthermore, an optical display apparatus control program of exemplaryembodiment 19 is according to any of optical display apparatus controlprograms of exemplary embodiments 12 to 17, the first and second lightmodulator elements are particular-wavelength-regioned intensitymodulator elements to modulate an intensity of light in a particularwavelength region as to a plurality of different particular wavelengthregions of a wavelength region of light.

With this structure, in the case the program is read out by the computerand then the computer executes the process according to the program readout, it is possible to obtain the operation and effect equivalent tothat of the optical display apparatus of exemplary embodiment 9.

[Exemplary Embodiment 20]

Furthermore, an optical display apparatus control program of exemplaryembodiment 20 is according to any of optical display apparatus controlprograms of exemplary embodiments 12 to 19, the second light modulatorelement having a higher resolution than the first light modulatorelement.

With this structure, in the case the program is read out by the computerand then the computer executes the process according to the program readout, it is possible to obtain the operation and effect equivalent tothat of the optical display apparatus of exemplary embodiment 10.

[Exemplary Embodiment 21]

Meanwhile, in order to address or achieve the above object, a lightpropagation characteristic control method of exemplary embodiment 21 isa method to be applied to an optical system to modulate light from alight source through a first light modulator element having a pluralityof pixels capable of independently controlling light propagationcharacteristics and a second light modulator element having a pluralityof pixels capable of independently controlling light propagationcharacteristics. The method includes:

-   -   tentatively deciding a light propagation characteristic of each        pixel of the second light modulator element depending upon        display data; and    -   deciding a light propagation characteristic of each pixel of the        first light modulator element depending upon a light propagation        characteristic tentatively decided by the light propagation        characteristic tentative deciding and the display data;    -   the light propagation characteristic tentative deciding is        allowed to tentatively decide a light propagation characteristic        of each pixel of the second light modulator element by use of a        gamma characteristic expression to calculate an intensity level        of light to be modulated through the first and second light        modulator elements depending upon an intensity level of light to        be modulated through the second light modulator element and a        gamma coefficient.

This provides the effect equivalent to that of the light propagationcharacteristic control apparatus of exemplary embodiment 1.

[Exemplary Embodiment 22]

Meanwhile, in order to address or achieve the above object, an opticaldisplay apparatus control method of exemplary embodiment 22 is a methodto control an optical display apparatus having a light source, a firstlight modulator element having a plurality of pixels capable ofindependently controlling light propagation characteristics and a secondlight modulator element having a plurality of pixels capable ofindependently controlling light propagation characteristics, to therebymodulate light from the light source through the first and second lightmodulator elements and display an image. The method includes:

-   -   tentatively deciding a light propagation characteristic of each        pixel of the second light modulator element depending upon        display data;    -   deciding a light propagation characteristic of each pixel of the        first light modulator element depending upon the light        propagation characteristic tentatively decided by the light        propagation characteristic tentative deciding and the display        data;    -   deciding a control value of each pixel of the first light        modulator element depending upon the light propagation        characteristic decided by the first light propagation        characteristic deciding;    -   deciding a light propagation characteristic of each pixel of the        second light modulator element depending upon the light        propagation characteristic decided by the first light        propagation characteristic deciding and display data; and    -   deciding a control value of each pixel of the second light        modulator element depending upon the light propagation        characteristic decided by the second light propagation        characteristic deciding;

The light propagation characteristic tentative deciding is allowed totentatively decide a light propagation characteristic of each pixel ofthe second light modulator element by use of a gamma characteristicexpression to calculate an intensity level of light to be modulatedthrough the first and second light modulator elements depending upon anintensity level of light to be modulated through the second lightmodulator element and a gamma coefficient.

This provides the effect equivalent to that of the optical displayapparatus of exemplary embodiment 2.

Here, the second light propagation characteristic deciding may be of anystructure provided that the light propagation characteristic of eachpixel of the second light modulator element is to be decided dependingupon the light propagation characteristic decided by the first lightpropagation characteristic deciding and display data. It may be made todecide a light propagation characteristic of each pixel of the secondlight modulator element depending upon an operation result or conversionresult of an operation or conversion carried out depending upon a lightpropagation characteristic decided by the first light propagationcharacteristic deciding without limited to the light propagationcharacteristic decided by the first light propagation characteristicdeciding. For example, because the control value decided by the firstcontrol-value deciding is decided depending upon the light propagationcharacteristic decided by the first light propagation characteristicdeciding, the second light propagation characteristic deciding isallowed to decide a light propagation characteristic of each pixel ofthe second light modulator element depending upon the control valuedecided by the first control-value deciding and display data.

[Exemplary Embodiment 23]

Furthermore, an optical display apparatus control method of exemplaryembodiment 23 is according to the optical display apparatus controlmethod of exemplary embodiment 22. The light propagation characteristictentative deciding calculates the intensity level n with use of thefollowing gamma characteristic expression by taking as Rp an intensitylevel of a pixel p in the display data, as Rmax a maximum value ofintensity level in the display data, as n an intensity level of a pixelof second light modulator element corresponding to the pixel p, as m acoefficient in accordance with the number of levels of the second lightmodulator element and as γ a gamma coefficient,Rp=Rmax×(n/m)^(γ)and tentatively decides a light propagation characteristic of the pixelof second light modulator element corresponding to the pixel p based onthe calculated intensity level n.

This provides an effect equivalent to that of the optical displayapparatus of exemplary embodiment 3.

[Exemplary Embodiment 24]

Furthermore, an optical display apparatus control method of exemplaryembodiment 24 is according to the optical display apparatus controlmethod of exemplary embodiment 23, the coefficient m being set at avalue obtained by multiplying a multiplier greater than 1 to the numberof levels of the second light modulator element.

This provides an effect equivalent to that of the optical displayapparatus of exemplary embodiment 4.

[Exemplary Embodiment 25]

Furthermore, an optical display apparatus control method of exemplaryembodiment 25 is according to the optical display apparatus controlmethod of exemplary embodiments 23 or 24, wherein the gamma coefficientγ is set at 4 or greater.

This provides an effect equivalent to that of the optical displayapparatus of exemplary embodiment 5.

[Exemplary Embodiment 26]

Furthermore, an optical display apparatus control method of exemplaryembodiment 26 is according to the optical display apparatus controlmethod of exemplary embodiments 23 or 24, wherein the gamma coefficientγ is set at 0 or greater and ¼ or smaller.

This provides an effect equivalent to that of the optical displayapparatus of exemplary embodiment 6.

[Exemplary Embodiment 27]

Furthermore, an optical display apparatus control method of exemplaryembodiment 27 is according to any of the optical display apparatuscontrol methods of exemplary embodiments 22 to 26, the second lightmodulator element being a light modulator element decisive of aresolution of display.

This provides an effect equivalent to that of the optical displayapparatus of exemplary embodiment 7.

[Exemplary Embodiment 28]

Furthermore, an optical display apparatus control method of exemplaryembodiment 28 is according to any of the optical display apparatuscontrol methods of exemplary embodiments 22 to 27, one of the first andsecond light modulator elements being a particular-wavelength-regionedintensity modulator element to modulate an intensity of light in aparticular wavelength region as to a plurality of different particularwavelength regions of a wavelength region of light. The other of thefirst and second light modulator elements being anentire-wavelength-regioned modulator element to modulate an intensity oflight over the entire wavelength region.

This provides an effect equivalent to that of the optical displayapparatus of exemplary embodiment 8.

[Exemplary Embodiment 29]

Furthermore, an optical display apparatus control method of exemplaryembodiment 29 is according to any of the optical display apparatuscontrol methods of exemplary embodiments 22 to 27, the first and secondlight modulator elements being particular-wavelength-regioned intensitymodulator elements to modulate an intensity of light in a particularwavelength region as to a plurality of different particular wavelengthregions of a wavelength region of light.

This provides an effect equivalent to that of the optical displayapparatus of exemplary embodiment 9.

[Exemplary Embodiment 30]

Furthermore, an optical display apparatus control method of exemplaryembodiment 30 is according to any of the optical display apparatuscontrol methods of exemplary embodiments 22 to 29, the second lightmodulator element having a higher resolution than the first lightmodulator element.

This provides an effect equivalent to that of the optical displayapparatus of exemplary embodiment 10.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram showing a hardware configuration ofa projection display apparatus 100;

FIG. 2 is a schematic block diagram showing a hardware configuration ofa display control apparatus 200;

FIG. 3 is a figure showing a data structure of a control-value librarytable 400;

FIG. 4 is a figure showing a data structure of a control-value librarytable 420R;

FIG. 5 is a flowchart showing a display control process;

FIG. 6 is a schematic showing a tone mapping process;

FIG. 7 is a schematic showing the case of tentatively deciding atransmissivity T2 of a color-modulation light valve;

FIG. 8 is a schematic showing the case of calculating a transmissivityT1′ of an intensity-modulation light valve on a pixel-by-pixel basis ofthe color-modulation light valve;

FIGS. 9(a)-(c) are schematics showing the case of deciding atransmissivity T1 of each pixel of the intensity-modulation light valve;

FIGS. 10(a)-(c) are schematics showing the case of deciding atransmissivity T2 of each pixel of the color-modulation light valve;

FIG. 11 is a schematic showing an intensity level distribution in aresized image;

FIG. 12 is a graph showing a gamma characteristic in the case of settingat a gamma coefficient γ=2.2, m=256;

FIG. 13 is a schematic showing an intensity level distribution on animage formed by the color-modulation light valve;

FIG. 14 is a graph showing a gamma characteristic in the case of settingat a gamma coefficient γ=2.2, m=1024;

FIG. 15 is a schematic showing an intensity level distribution on animage formed by the color-modulation light valve;

FIG. 16 is a graph showing a gamma characteristic in the case of settingat a gamma coefficient γ=4.4, m=256;

FIG. 17 is a schematic showing an intensity level distribution on animage formed by the color-modulation light valve;

FIG. 18 is a schematic showing an intensity level distribution in aresized image;

FIG. 19 is a graph graph showing a gamma characteristic in the case ofsetting at a gamma coefficient γ=¼, m=256;

FIG. 20 is a schematic showing an intensity level distribution formed onan image by the color-modulation light valve;

FIG. 21 is a schematic block diagram showing a hardware configuration inthe case that a projection display apparatus 100 is structured byproviding intensity-modulation light valve and color-modulation lightvalve based on each three primary colors of RGB;

FIG. 22 is a schematic block diagram showing a hardware configuration inthe case that a projection display apparatus 100 is structured byproviding a relay lens 50 between the intensity modulator section 12 andthe color modulator section 14;

FIG. 23 is a schematic block diagram showing a hardware configuration inthe case that a projection display apparatus 100 is structured byproviding an intensity modulator section 12 on the light-exit side ofthe color modulator section 14;

FIG. 24 is a schematic block diagram showing a hardware configuration inthe case of structuring a projection display apparatus 100 as asingle-plated type;

FIG. 25 is a schematic block diagram showing a hardware configuration ofa projection display system 300;

FIG. 26 is a schematic block diagram showing a hardware configuration ofa projection display system 300;

FIG. 27 is a schematic block diagram showing a hardware configuration ofa display 400;

FIG. 28 is a figure showing a data structure of an input-value librarytable 440; and

FIG. 29 is a figure showing a data structure of an input-value librarytable 460.

DETAILED DESCRIPTION OF EMBODIMENTS

Referring to the drawings, explanations will be now made on an exemplaryembodiment of the present invention. FIGS. 1 to 17 are figuresillustrating the exemplary embodiments of a light propagationcharacteristic control apparatus, optical display apparatus, lightpropagation characteristic control program, optical display apparatuscontrol program, light propagation characteristic control method andoptical display apparatus control method, according to exemplaryembodiments of the invention.

The present exemplary embodiment is an application of the lightpropagation characteristic control apparatus, optical display apparatus,light propagation characteristic control program, optical displayapparatus control program, light propagation characteristic controlmethod and optical display apparatus control method of exemplaryembodiments of the invention, to a projection display apparatus 100, asshown in FIG. 1.

Referring to FIG. 1, explanation is first made on the structure of theprojection display apparatus 100.

FIG. 1 is a schematic block diagram showing a hardware construction ofthe projection display apparatus 100.

The projection display apparatus 100 is constructed, as shown in FIG. 1,with a light source 10, an intensity modulator section 12 to modulatethe light intensity in the entire wavelength region of light incidentfrom the light source 10, a color modulator section 14 to modulate thelight intensity of RGB primary colors in a wavelength region of lightincident from the intensity modulator section 12, and a projectorsection 16 to project onto a screen (not shown) the light incident fromthe color modulator section 14.

The intensity modulator section 12 is made up with a liquid-crystallight valve 30 having a plurality of pixels independently controllablein transmissivity and arranged in a matrix form, and two fly-eye lenses32 a, 32 b. The light from the light source 10 is modulated in intensityover the entire wavelength region by the liquid-crystal light valve 30.The modulated light is exited to the color modulator section 14 throughthe fly-eye lenses 32 a, 32 b.

The color modulator section 14 is made up by three liquid-crystal lightvalves 40R, 40G, 40B having a plurality of pixels independentlycontrollable in transmissivity and arranged in a matrix form to have ahigher resolution than that of the liquid-crystal light valve 30, fivefield lens 42R, 42G, 42B₁-42B₃, two dichroic mirrors 44 a, 44 b, threemirrors 46 a, 46 b, 46 c and a dichroic prism 48. At first, the lightfrom the intensity modulator section 12 is separated into RGB threeprimary colors of red, green and blue by the dichroic mirrors 44 a, 44 band then incident on the liquid-crystal light valves 40R-40B through thefield lenses 42R, 42G, 42B₁-42B₃ and mirrors 46 a-46 c. Then, theseparated light intensities of RGB three primary colors are respectivelymodulated by the liquid-crystal light valves 40R-40B. The modulated RGBthree primary colors of light are collected together by the dichroicprism 48 and exited to the projector section 16.

The liquid-crystal light valves 30, 40R-40B are active-matrixliquid-crystal display devices having a TN liquid crystal sandwichedbetween a glass substrate formed with a matrix form of pixel electrodesand switching elements, such as thin-film transistor elements andthin-film diodes, to drive them and a glass substrate formed with acommon electrode over the entire surface thereof, wherein a polarizerplate is arranged on an outer surface thereof. The liquid-crystal lightvalves 30, 40R-40B operate on normally white mode. Namely, it takes awhite/light (transmission) state under non-application of voltage and ablack/dark (non-transmission) state under application of voltage, thusbeing placed under analog-control to have an intensity level betweenthem according to a given control value.

Meanwhile, the projection display apparatus 100 has a display controlapparatus 200 (not shown) to control the liquid-crystal light valve 30and liquid-crystal light valves 40R-40B. Hereinafter, the liquid-crystallight valves 40R-40B are generally referred to as color-modulation lightvalves while the liquid-crystal light valve 30 is referred to as anintensity-modulation light valve in order to distinguish it from thecolor-modulation light valve. In this exemplary embodiment, thecolor-modulation light valve decides a resolution of display (resolutionto be perceived by the observer who is viewing an image on theprojection display apparatus 100).

Referring to FIGS. 2 to 6, the structure of the display controlapparatus 200 is now explained in detail.

FIG. 2 is a schematic block diagram showing a hardware configuration ofthe display control apparatus 200.

The display control apparatus 200 is constructed, as shown in FIG. 2, bya CPU 70 for control of operation and system overall according to acontrol program, a ROM 72 previously storing a control program, etc. forthe CPU 70 in a predetermined domain, a RAM 74 for storing data read outof the ROM 72, etc. or an operation result required in the course ofoperation in the CPU 70, and an I/F 78 mediating to input/output datato/from external apparatuses. These are mutually connected for exchangeof data through a bus 79 as a signal line for data transfer.

The I/F 78 is connected with, as external devices, a light-valve drivedevice 80 to drive the intensity-modulation light valve andcolor-modulation light valve, a storing device 82 to store data, table,etc. as files, and a signal line for connection to the external network199.

The storing device 82 is stored with HDR display data.

HDR display data is image data capable of realizing a high-intensitydynamic range not to be realized by the related art sRGB image format orthe like, storing pixel values representative of intensity levels of allthe pixels of an image. At present, it is used particularly in the CGworld, to synthesize a CG object with the actual scene. Although thereare various image forms, those mostly are of the form storing pixelvalues on the floating-point scheme in order to realize a higherlight-intensity dynamic range than the related art image format of sRGBor the like. Meanwhile, it is also a feature that storage value is avalue related to physical radiance (W/(sr·m²)) not taking account ofhuman visual characteristic or to luminance (cd/m²) taking account ofhuman visual characteristic. In this exemplary embodiment, HDR displaydata uses a form storing, as floating-point values, pixel valuesrepresenting radiance levels based on RGB three primary colors of onepixel. For example, a value (1.2, 5.4, 2.3) is stored as a pixel valueas to one pixel.

HDR display data is generated by taking an HDR image in a highlight-intensity dynamic range and based on the HDR image thus taken.However, with the film camera or digital still camera presentlyavailable, it is impossible to take, at one time, an HDR image having ahigh light-intensity dynamic range in the natural world. For thisreason, one HDR image is generated from a plurality of photographicimages changed in exposure by a certain way. Incidentally, the HDRdisplay data generation method is detailed in related art document “P.E. Debevec, J. Malik, “Recovering High Dynamic Range Radiance Maps fromPhotographs”, Proceedings of ACM SIGGAPH97, pp.367-378 (1997)”, forexample.

Meanwhile, the storing device 82 is stored with a control-value librarytable 400 in which control values of the intensity-modulation lightvalve are registered.

FIG. 3 is a figure showing a data structure of the control-value librarytable 400.

In the control-value library table 400, one record is registered percontrol value of the intensity-modulation light valve, as shown in FIG.3. Each record is constituted including a field registered with acontrol value of the intensity-modulation light valve and a fieldregistered with a transmissivity of the intensity-modulation lightvalve.

In the example of FIG. 3, the first-staged record has entries of “0” asa control value and “0.003” as a transmissivity. This indicates thatoutputting a control value “0” to the intensity-modulation light valvegives a transmissivity 0.3% of the intensity-modulation light valve.Although FIG. 3 showed the case that the intensity-modulation lightvalve has the number of levels of 4 bits (0-15 values), actually thereare registered records corresponding to the number of levels of theintensity-modulation light valve. For example, for the number of levelsof 8 bits, 256 records are to be registered.

Meanwhile, the storing device 82 is stored, for each color-modulationlight valve, with control value library tables 420R, 420G, 420B havingentries of control values of the relevant intensity-modulation lightvalve.

FIG. 4 is a figure showing a data structure of the control-value librarytable 420R.

In the control-value library table 420R, one record is registered percontrol value for the liquid-crystal light valve 40R, as shown in FIG.4. Each record is constituted including a field registered with acontrol value of the liquid-crystal light valve 40R and a fieldregistered with a transmissivity of the liquid-crystal light valve 40R.

In the example of FIG. 4, the first-staged record has entries of “0” asa control value and “0.004” as a transmissivity. This indicates thatoutputting a control value “0” to the liquid-crystal light valve 40Rgives a transmissivity 0.4% of the liquid-crystal light valve 40R.Although FIG. 4 showed the case that the color-modulation light valvehas the number of levels of 4 bits (0-15 values), actually there areregistered records in the number corresponding to the number of levelson the color-modulation light valve. For example, for the number oflevels of 8 bits, 256 records are to be registered.

Meanwhile, although not especially shown is a data structure of thecontrol-value library tables 420G, 420B, they have a similar datastructure to the control-value library table 420R. However, thedifference from the control-value library table 420R lies in adifference of the transmissivity corresponding to the same controlvalue.

Next, explanation is made on the configuration of the CPU 70 and theprocess to be executed by the CPU 70.

The CPU 70 includes a micro-processing unit (MPU) or the like, to startup a predetermined program stored in a predetermined domain of the ROM72 and execute a display control process shown in a flowchart of FIG. 5.

FIG. 5 is a flowchart showing the display control process.

The display control process is a process to decide control valuesrespectively of the intensity-modulation light valve and thecolor-modulation light valve depending upon HDR display data and therebydrive the intensity-modulation light valve and color-modulation lightvalue depending upon the decided control values. In the case it isexecuted in the CPU 70, the process first moves to step S100 as shown inFIG. 5.

At step S100, HDR display data is read out of the storing device 82.

Then, the process moves to step S102 to analyze the HDR display dataread out and calculate a maximum value Rmax, a minimum value, a meanvalue, etc. of intensity levels of each color while taking account of apixel-value histogram and a while point. The analysis result is for usein automatic image correction, e.g. lightening a darker scene, darkeningan excessively light scene, and enhancing a middle-contrasted zone, orfor use in tone mapping.

Next, the process moves to step S104 where the intensity levels of HDRdisplay data are tone-mapped onto the light-intensity dynamic range ofthe projection display apparatus 100 based on the analysis result instep S102.

FIG. 6 is a figure for explaining the process of tone mapping process.

It is assumed that, as a result of analyzing HDR display data, theintensity levels included in the HDR display data have a minimum valueof Smin and a maximum value of Smax. Meanwhile, the projection displayapparatus 100 assumably has a light-intensity dynamic range having aminimum value of Dmin and a maximum value of Dmax. In the example ofFIG. 6, because Smin is smaller than Dmin and Smax is greater than Dmax,it is impossible to suitably display the HDR display data as it is.Consequently, normalization is made to place the histogram of Smin-Smaxto within the range of Dmin-Dmax.

Incidentally, tone mapping is detailed in related art document “F.Drago, K. Myszkowski, T. Annen, N. Chiba, “Adaptive Logarithmic MappingFor Displaying High Contrast Scenes”, Eurographics 2003, (2003)”, forexample.

Then, the process moves to step S106 where the HDR image is resized(expanded or contracted) to a resolution of the color-modulation lightvalve. At this time, the HDR image is resized while keeping the aspectratio of the HDR image. Resize techniques include, for example,mean-value method, intermediate-value method and nearest-neighbormethod.

Then, the process moves to step S108 where light modulation ratio Tp iscalculated on each pixel of the resized image by use of the aboveequation (1), depending upon an intensity level Rp of each pixel of theresized image and radiance Rs of the light source 10.

Then, the process moves to step S110, to take as Rp an intensity levelat pixel p of the resized image, as Rmax a maximum intensity level, as nan intensity level at pixel p of the color-modulation light valve, as ma coefficient in accordance with the number of levels of thecolor-modulation light valve and as γ a gamma coefficient, thuscalculating an intensity level n by use of the following equations (3)and (4). This is carried out on all the pixels of the color-modulationlight valve, based on RGB three primary colors.Rp=Rmax×(n/m)^(γ)  (3)n=exp((log(Rp)−log(Rmax))/γ+log(m))   (4)

Then, tentatively decided is a transmissivity T2 of each pixel of thecolor-modulation light valve depending upon a calculated intensity leveln. Because the intensity level n corresponds to a control value for thecolor-modulation light valve, it is satisfactory to read atransmissivity corresponding to the intensity level n out of thecontrol-value library tables 420R-420B.

Then, the process moves to step S12 where the transmissivity T1′ of theintensity-modulation light valve is calculated on a pixel-by-pixel basisof the color-modulation light valve by use of the above equation (2),depending upon the calculated light modulation ratio Tp, the tentativelydecided transmissivity T2 and the gain G. Here, because thecolor-modulation light valve is constituted by three liquid-crystallight valves 40R-40B, the transmissivity T1′ is calculated based on RGBthree primary colors as to a same pixel. Contrary to this, because theintensity-modulation light valve is constituted by one liquid-crystallight valve 30, a mean value of those, etc. is calculated as T1′ of therelevant pixel.

Then, the process moves to step S114 where, for each pixel of theintensity-modulation light valve, a weighted mean value of thetransmissivities T1′ calculated on the pixel of color-modulation lightvalve overlapping, on the optical path, with the relevant pixel, as atransmissivity T1 of the relevant pixel. Weighting is by the area ratioof the overlapped pixels.

Then, the process moves to step S116 where, for each pixel of theintensity-modulation light valve, a control value corresponding to thetransmissivity T1 calculated on that pixel is read out of thecontrol-value library table 400. The control value thus read out isdecided as a control value at the relevant pixel. In reading out acontrol value, a transmissivity most approximate to the calculatedtransmissivity T1 is searched through the control-value library table400, to thereby read out a control value corresponding to thetransmissivity found out by the search. By performing the search withusing, for example, the dichotomizing search technique, rapid search isto be realized.

Then, the process moves to step S118 where, for each pixel of thecolor-modulation light valve, calculated is a weighted mean value of thetransmissivities T1 decided on the pixel of intensity-modulation lightvalve overlapping, on the optical path, with that pixel. Based on thecalculated mean value, the light modulation ratio Tp calculated at stepS108 and the gain G, a transmissivity T2 of the pixel is calculated byuse of the foregoing equation (2). Weighting is by the area ratio of theoverlapped pixels.

Then, the process moves to step S120 where, for each pixel of thecolor-modulation light valve, a control value corresponding to thetransmissivity T2 calculated on that pixel is read out of thecontrol-value library tables 420R-420B. The control value thus read outis decided as a control value at the relevant pixel. In reading out acontrol value, a transmissivity most approximate to the calculatedtransmissivity T2 is searched through the control-value library tables420R-420B, to read out a control value corresponding to thetransmissivity found out by the search. By performing the search withusing, for example, the dichotomizing search technique, rapid search isto be realized.

Then, the process moves to step S122 where the control values decided atsteps S16, S120 are outputted to the light-valve drive device 80,thereby driving the intensity-modulation light valve and thecolor-modulation light valve and projecting a display image. Thus, theprocess in series is ended for return to the former process.

Referring to FIGS. 7 to 17, explanation is made on the operation of thepresent exemplary embodiment.

In the below, explanation is by an exemplification that any of thecolor-modulation light valves has a resolution of horizontally 18pixels×vertically 12 pixels and the number of levels of 8 bits while theintensity-modulation light valve has a resolution of horizontally 15pixels×vertically 10 pixels and the number of levels of 8 bits.

In the display control apparatus 200, HDR display data is read outthrough steps S100-S104 and the HDR display data thus read out is placedunder analysis. Depending upon a result of the analysis, the intensitylevels of HDR display data are tone-mapped onto the light-intensitydynamic range of the projection display apparatus 100. Then, throughstep S106, the HDR image is resized to the resolution of thecolor-modulation light valve.

Next, through step S108, light modulation ratio Tp is calculated foreach pixel of the resized image. For example, the light modulation ratioTp of the resized-image pixel p is given as (1.2, 5.4, 2.3)/(10000,10000, 10000)=(0.00012, 0.00054, 0.00023) provided that the pixel p hasan intensity level Rp (R, G, B) of (1.2, 5.4, 2.3) and the light source10 has an radiance Rs (R, G, B) of (10000, 10000, 10000).

FIG. 7 is a schematic figure showing a case to tentatively decide atransmissivity T2 of the color-modulation light valve.

Then, through step S110, tentatively decided is a transmissivity T2 ofeach pixel of the color-modulation light valve. Provided that the upperleft 4 segments of the color-modulation light valve are denoted as p21(upper left), p22 (upper right), p23 (lower left) and p24 (lower right),then the intensity level n on the pixel p21 is calculated by use of theabove equations (3) and (4) when taking as Rp the intensity level at thepixel corresponding to the pixel p21 of the resized image. Then, thetransmissivity corresponding to the calculated intensity level n is readout of the control-value library tables 420R-420B. Thus, the read-outtransmissivity is provided for a transmissivity T21 of the pixel p21, asshown in FIG. 7. The transmissivities T22-T24 of the pixels p22-p24 canalso be determined by calculating the intensity levels n by the aboveequations (3) and (4), similarly to the pixel p21.

FIG. 8 is a schematic figure showing a case to calculate atransmissivity T1′ of the intensity-modulation light valve on apixel-by-pixel basis of the color-modulation light valve.

Then, through step S112, a transmissivity T1′ of theintensity-modulation light valve is calculated on a pixel-by-pixel basisof the color-modulation light valve. In the case putting the eye on thepixels p21-p24, the corresponding transmissivities T11-T14 of theintensity-modulation light valve can be calculated by the followingequations (5)-(8) as shown in FIG. 8 provided that the pixels p21-p24have light modulation ratios of Tp1-Tp4 and a gain G of “1”.

By using numerals, calculation is made actually. In the case ofTp1=0.00012, Tp2=0.05, Tp3=0.03, Tp4=0.01, T21=0.1, T22=0.2, T23=0.3 andT24=0.4, the following equations (5)-(8) provide T11=0.0012, T12=0.25,T13=0.1 and T14=0.025.T 11=Tp 1/T 21   (5)T 12=Tp 2/T 22   (6)T 13=Tp 3/T 23   (7)T 14=Tp 4/T 24   (8)

FIGS. 9(a)-(c) are figures showing a case to decide a transmissivity T1of each pixel of the color-modulation light valve.

Then, through step S114, decided is a transmissivity T1 of each pixel ofthe intensity-modulation light valve. Provided that the upper left foursegments of the intensity-modulation light valve are denoted as p11(upper left), p12 (upper right), p13 (lower left) and p14 (lower right),then the pixel p11 lies overlapping, on the optical path, with thepixels p21-p24 because of different resolution between thecolor-modulation light valve and the intensity-modulation light valve asshown in FIG. 9(a). Because the color-modulation light valve has aresolution of 18×12 and the intensity-modulation light valve has aresolution of 15×10, the pixel p11 can be segmented as 6×6 rectangulardomains by virtue of its least common multiple. The pixel p11 and thepixels p21-p24 have an overlapping area ratio of 25:5:5:1 as shown inFIG. 9(b). Accordingly, the transmissivity T15 at the pixel p11 can becalculated by the following equation (9), as shown in FIG. 9(c).

By using numerals, calculation is made actually. In the case ofT11=0.0012, T12=0.5, T13=0.2 and T14=0.002, the following equation (9)provides T15=0.1008.T 15=(T 11×25+T 12×5+T 13×5+T 14×1)/36   (9)

As for the transmissivities T16-T18 at the pixels P12-P14, a weightedmean value by area ratio can be decided similarly to the pixel p11.

Then, through step S116, based on each pixel of the intensity-modulationlight valve, read out is a control value corresponding to thetransmissivity T1 calculated on the pixel from the control-value librarytable 400. The control value thus read out is decided as a control valueat the relevant pixel. For example, because of T15=0.1008, thecontrol-value library table 400 is looked up. Then, 0.09 comes as themost approximate value, as shown in FIG. 3. Consequently, “8” is read asa control value of the pixel p11 from the control-value library table400.

FIGS. 10(a)-(c) are figures showing a case to decide a transmissivity T2of each pixel of the color-modulation light valve.

Then, through step S118, decided is a transmissivity T2 of each pixel ofthe color-modulation light valve. Because of different resolutionbetween the color-modulation light valve and the intensity-modulationlight valve as shown in FIG. 10(a), the pixel p24 overlaps, on the lightpath, with the pixels p11-p14, as shown in FIG. 10(a). Because thecolor-modulation light valve has a resolution of 18×12 and theintensity-modulation light valve has a resolution of 15×10, the pixelp24 can be segmented into 5×5 rectangular domains by virtue of its leastcommon multiple. The pixel p24 and the pixels p11-p14 have anoverlapping area ratio of 1:4:4:16 as shown in FIG. 10(b). Accordingly,when putting the eye on the pixel p24, the corresponding transmissivityT19 of the intensity-modulation light valve can be calculated by thefollowing equation (10). Then, the transmissivity T28 at the pixel p24,provided that the gain G is “1”, can be calculated by the followingequation (11) as shown in FIG. 10(c).

By using numerals, calculation is made actually. In the case ofT15=0.09, T16=0.33, T17=0.15, T18=0.06 and Tp4=0.01, the followingequations (10) and (11) provide T19=0.1188 and T28=0.0842.T 19=(T 15×1+T 16×4+T 17×4+T 18×16)/25   (10)T 28=Tp 4/T 19   (11)

For the transmissivities T25-T27 at the pixels P21-P23, a weighted meanvalue by area ratio can be decided similarly to the pixel p24.

Then, through step S120, for each pixel of the color-modulation lightvalve, read out is a control value corresponding to the transmissivityT2 calculated on that pixel from the control-value library tables420R-420B. The control value thus read out is decided as a control valueof the relevant pixel. For example, in the case that T28=0.0842concerning the pixel p24 of the liquid-crystal light valve 40R, 0.07 isthe most approximate value as shown in FIG. 4 when looking up thecontrol-value library table 420R. Accordingly, “7” is read out as acontrol value of the pixel p24 from the control-value library table420R.

Then, through step S122, the decided control value is outputted onto thelight-valve drive device 80. This drives the intensity-modulation lightvalve and the color-modulation light valve, to project a display image.

Explanation is now made on an exemplary embodiment with the setting of agamma coefficient γ=2.2, m=256.

FIG. 11 is a schematic figure showing an intensity level distribution onthe resized image.

In the resized image of FIG. 11, the intensity level Rp is “20000” atthe sun, the intensity level Rp is “12000” at the sky, the intensitylevel Rp is “6000” at the cloud, the intensity level Rp is “200” at themountain on the left, the intensity level Rp is “80” at the mountain onthe right, the intensity level Rp is “5” at the tree and the intensitylevel Rp is “8” at the shade of tree. Accordingly, the maximum intensitylevel Rmax is given as “20000”.

FIG. 12 is a graph showing a gamma characteristic with the setting of agamma coefficient γ=2.2, m=256.

FIG. 13 is a schematic figure showing an intensity level distribution ofan image formed by the color-modulation light valve.

For the respective areas in the resized image of FIG. 11, in the casecalculating the intensity levels n on the corresponding pixels of thecolor-modulation light valve by use of the gamma characteristicexpression of FIG. 12, at first the intensity level n on the sun isgiven as “256”. However, this value is beyond the number of levels “255”of the color-modulation light valve, it is set to the maximum value“255” as shown in FIG. 13. Meanwhile, the intensity level n on the skyis given “203”, the intensity level n on the cloud is “148”, theintensity level n on the mountain on the left is “32”, the intensitylevel n on the mountain on the right is “21”, the intensity level n onthe tree is “6” and the intensity level n on the shade of tree is “7”.

Explanation is now made on an exemplary embodiment with the setting of agamma coefficient γ=2.2, m=1024.

FIG. 14 is a graph showing a gamma characteristic set with a gammacoefficient γ=2.2, m=1024.

FIG. 15 is a schematic figure showing an intensity level distributionformed by the color-modulation light valve.

For the respective areas in the resized image of FIG. 11, in the casecalculating the intensity levels n of the corresponding pixels of thecolor-modulation light valve by use of the gamma characteristicexpression of FIG. 14, at first the intensity level n on the sun isgiven as “1024”. However, this value is beyond the number of levels“255” of the color-modulation light valve, it is set to the maximumvalue “255” as shown in FIG. 15. Likewise, the intensity levels n of thesky and the cloud are both set to the maximum value “255”. Meanwhile,the intensity level n on the mountain on the left is given “126”, theintensity level n on the mountain on the right is “83”, the intensitylevel n on the tree is “24” and the intensity level n on the shade oftree is “29”.

The sensitivity to intensity levels, in human visual perception, ishigher in the lower region of intensity level (in the dark).Accordingly, the influence upon visual perception is greater rather bycontrol of a color-modulation light valve decisive of the resolution ofdisplay, which enables the reproduction of dark intensity levels withgreater detail. Contrary to this, the sensitivity to intensity levels,in human visual perception, is lower in the fully higher region ofintensity level (in the light). There is less effect upon visualperception even by control of an intensity-modulation light valve.Therefore, this can reduce the possibility of deteriorated imagequality.

Explanation is now made on an exemplary embodiment with the setting of agamma coefficient γ=4.4, m=256.

FIG. 16 is a graph showing a gamma characteristic set with a gammacoefficient γ=4.4, m=256.

FIG. 17 is a schematic figure showing an intensity level distributionformed by the color-modulation light valve.

For the respective areas in the resized image of FIG. 11, in the casecalculating the intensity levels n on the corresponding pixels of thecolor-modulation light valve by use of the gamma characteristicexpression of FIG. 16, at first the intensity level n on the sun isgiven as “256”. However, this value is beyond the number of levels “255”of the color-modulation light valve, it is set to the maximum value“255” as shown in FIG. 17. Meanwhile, the intensity levels n of the skyis given as “228”, the intensity level n on the cloud is “195”, theintensity level n on the mountain on the left is “90”, the intensitylevel n on the mountain on the right is “73”, the intensity level n onthe tree is “39” and the intensity level n on the shade of tree is “43”.

The sensitivity to intensity levels, in human visual perception, ishigher in the lower region of intensity level (in the dark).Accordingly, the influence upon visual perception is greater rather bycontrol of a color-modulation light valve decisive of the resolution ofdisplay, which enables the reproduction of dark intensity levels withgreater detail. Contrary to this, the sensitivity to intensity levels,in human visual perception, is lower in the fully higher region ofintensity level (in the light). There is less effect upon visualperception even by control of an intensity-modulation light valve.Therefore, this can reduce the possibility to deteriorate image quality.

In this manner, this exemplary embodiment tentatively decides atransmissivity T2 of each pixel of the color-modulation light valve bythe gamma characteristic expression depending upon the HDR display data.Based on the tentatively decided transmissivity T2 and the HDR displaydata, decided is a transmissivity T1 of each pixel of theintensity-modulation light valve. Based on the decided transmissivityT1, decided is a control value of each pixel of the intensity-modulationlight valve. Based on the decided transmissivity T1 and the HDR displaydata, decided is a transmissivity T2 of each pixel of thecolor-modulation light valve. Based on the decided transmissivity T2,decided is a control value for each pixel of the color-modulation lightvalve.

Due to this, because the light from the light source 10 is modulatedthrough the intensity-modulation and color-modulation light valves, itis possible to realize a comparatively high dynamic range and the numberof levels. Meanwhile, because of deciding the transmissivity T2 of eachpixel of the color-modulation light valve by use of the gammacharacteristic expression, it is possible to obtain an image reduced inluminance and color irregularities and hence reduce the possibility todeteriorate image quality as compared to the related art. Furthermore,because the gamma characteristic expression is comparatively simple inoperation, it is possible to comparatively rapidly determine atransmissivity T2 for each pixel of the color-modulation light valve.Furthermore, because of no necessity to hold intensity tables in thenumber corresponding to the number of levels, there is no substantialincrease in the size and generation time of an intensity table ascompared to the related art even when increasing the number of levels.

Furthermore, the present exemplary embodiment takes the intensity levelon the pixel p of the resized image as Rp, the maximum intensity levelas Rmax, the intensity level on the pixel p of the color-modulationlight valve as n, the coefficient corresponding to the number of levelsof the color-modulation light valve as m, and the gamma coefficient asγ, to calculate the intensity level n by use of the foregoing equations(3) and (4). Based on the calculated intensity level n, tentativelydecided is a transmissivity T2 of the pixel corresponding to the pixel pof the color-modulation light valve.

Because this can obtain an image reduced in luminance and colorirregularities, it is possible to further reduce the possibility ofdeteriorated image quality.

Furthermore, in the present exemplary embodiment, the coefficient m wasset four times the number of levels of the color-modulation light valve.

This can precisely reproduce the dark intensity level of an image formedby the color-modulation light valve as compared to the case with asetting of the coefficient m at the number of levels of thecolor-modulation light valve, hence further reducing the possibility ofdeteriorated image quality.

Furthermore, the present exemplary embodiment set the gamma coefficientγ at 4 or greater.

This can precisely reproduce the dark intensity level of an image formedby the color-modulation light valve as compared to the case with asetting of the gamma coefficient γ at less than 4, thus further reducingthe possibility of deteriorated image quality.

Furthermore, in the present exemplary embodiment, the color-modulationlight valve is a light modulator element decisive of the resolution ofdisplay.

Because this allows to decide later the transmissivity T2 of thecolor-modulation light valve decisive of the resolution of display, itis possible to suppress the influence of error and further reduce thepossibility to deteriorate image quality.

Furthermore, in the present exemplary embodiment, the transmissivity T1′of the intensity-modulation light valve is calculated on apixel-by-pixel basis of the color-modulation light valve depending upona tentatively decided transmissivity T2 and HDR display data. Dependingupon a calculated transmissivity T1′, calculated is the transmissivityT1 of each pixel of the intensity-modulation light valve.

Where the intensity-modulation light valve and the color-modulationlight valve respectively have different resolutions, it is easier inprocess to calculate a transmissivity T1 of each pixel of theintensity-modulation light valve after once calculating a transmissivityT1′ of the intensity-modulation light valve on a pixel-by-pixel basis ofthe color-modulation light valve depending upon a tentatively decidedtransmissivity T2, rather than directly calculating a transmissivity T1of each pixel of the intensity-modulation light valve depending upon atentatively decided transmissivity T2. Accordingly, in the case that theintensity-modulation light valve and the color-modulation light valverespectively have different resolutions, it is possible to comparativelyeasily calculate a transmissivity T1 of each pixel of theintensity-modulation light valve.

Furthermore, in the present exemplary embodiment, for each pixel of theintensity-modulation light valve, a transmissivity T1 of that pixel iscalculated depending upon a transmissivity T1′ calculated on the pixelof color-modulation light valve overlapping, on the optical path, withthat pixel.

Due to this, when the intensity-modulation light valve and thecolor-modulation light valve respectively have different resolutions,the transmissivity T1 of each pixel of the intensity-modulation lightvalve is given a comparatively suitable value for the transmissivity T2at the pixel of color-modulation light valve overlapping, on the opticalpath, with that pixel. Accordingly, it is possible to further reduce thepossibility of deteriorated image quality. Also, it is possible tofurther easily calculate a transmissivity T1 of each pixel of theintensity-modulation light valve.

Furthermore, in the present exemplary embodiment, for each pixel of theintensity-modulation light valve, calculated is a weighted mean value ofthe transmissivities T1 calculated on the pixel of color-modulationlight valve overlapping, on the optical path, with that pixel, as atransmissivity T1 of the relevant pixel.

Due to this, where the intensity-modulation light valve and thecolor-modulation light valve respectively have different resolutions,the transmissivity T1 of each pixel of the intensity-modulation lightvalve is given a further suitable value for the transmissivity T2 at thepixel of color-modulation light valve overlapping, on the optical path,with that pixel. Thus, it is possible to further reduce the possibilityof deteriorated image quality. Also, it is possible to further easilycalculate the transmissivity T1 of each pixel of theintensity-modulation light valve.

Furthermore, in the present exemplary embodiment, for each pixel of thecolor-modulation light valve, calculated is a transmissivity T2 of thatpixel depending upon the transmissivity T1 decided on the pixel ofintensity-modulation light valve overlapping, on the optical path, withthat pixel.

Due to this, where the intensity-modulation light valve and thecolor-modulation light valve respectively have different resolutions,the transmissivity T2 of each pixel of the color-modulation light valveis given a comparatively suitable value for the transmissivity T1 at thepixel of intensity-modulation light valve overlapping, on the opticalpath, with that pixel. Thus, it is possible to further reduce thepossibility of deteriorated image quality. Also, it is possible tocomparatively easily calculate the transmissivity T2 of each pixel ofthe color-modulation light valve.

Furthermore, in the present exemplary embodiment, for each pixel of thecolor-modulation light valve, calculated is a weighted mean value of thetransmissivities T1 decided on the pixel of intensity-modulation lightvalve overlapping, on the optical path, with the pixel, therebycalculating a transmissivity T2 of that pixel depending upon the meanvalue.

Due to this, where the intensity-modulation light valve and thecolor-modulation light valve respectively have different resolutions,the transmissivity T2 of each pixel of the color-modulation light valveis given a further suitable value for the transmissivity T1 at the pixelof intensity-modulation light valve overlapping, on the optical path,with that pixel. Thus, it is possible to further reduce the possibilityof deteriorated image quality. Also, it is possible to comparativelyeasily calculate the transmissivity T2 of each pixel of thecolor-modulation light valve.

Furthermore, in the present exemplary embodiment, theintensity-modulation light valve is used as a first-stagedlight-modulation element and the color-modulation light valves are usedas a second-staged light-modulation element, respectively.

Due to this, it is satisfactory to merely add one light-modulationelement to the related art projection display apparatus. Therefore, theprojection display apparatus 100 can be structured comparatively easily.

In the above exemplary embodiment, the intensity-modulation light valvecorresponds to the first light-modulation element of exemplaryembodiments 1, 2, 8, 10 to 12, 18, 20 to 22, 28 or 30 or to the entirewavelength regioned intensity-modulation element of exemplaryembodiments 8, 18 or 28. Meanwhile, the color-modulation light valvecorresponds to the second light-modulation element of exemplaryembodiments 1 to 4, 7, 8, 10 to 14, 17, 18, 20 to 24, 27, 28 or 30 or tothe particular wavelength regioned intensity-modulation element ofexemplary embodiments 8, 18 or 28. Meanwhile, the step S110 correspondsto the light-propagation-characteristic tentative deciding device ofexemplary embodiments 1 to 3, 11 to 13 or to thelight-propagation-characteristic tentative deciding of exemplaryembodiments 21 to 23 while the steps S112, S114 correspond to the firstlight-propagation-characteristic deciding device of exemplaryembodiments 1, 2, 11 or 12 or to the firstlight-propagation-characteristic deciding of exemplary embodiments 21 or22.

Meanwhile, in the above exemplary embodiment, the step S116 correspondsto the first control-value deciding device of exemplary embodiments 2 or12 or to the first control-value deciding of exemplary embodiment 22while the step S118 corresponds to the second lightpropagation-characteristic deciding device of exemplary embodiments 2 or12 or to the second light propagation-characteristic deciding ofexemplary embodiment 22. And the step S120 corresponds to the secondcontrol-value deciding device of exemplary embodiments 2 or 12 or to thesecond control-value deciding of exemplary embodiment 22.

Incidentally, in the above exemplary embodiment, the gamma coefficient γwas set at 4 or greater. However, this is not limitative, i.e. the gammacoefficient γ is preferably set at 0 or greater and ¼ or smaller.

Explanation is made on an exemplary embodiment with the setting of agamma coefficient γ=¼, m=256.

FIG. 18 is a schematic figure showing an intensity level distributionformed on the resized image.

In the resized image of FIG. 18, the intensity level Rp on the sun isgiven as “20000”, the intensity levels Rp on the sky are respectively“18300” (left), “19000” (upper center), “19500” (lower center) and“18400” (right), the intensity level Rp on the cloud is “17000”, theintensity levels Rp on the sea are respectively “18400” (left), “19700”(center) and “18500” (right), the intensity level Rp on the land is“18800” and the intensity level Rp on the snowman is “3000”.Accordingly, the maximum intensity level Rmax is given as “20000”.

FIG. 19 is a graph showing a gamma characteristic in the case the gammacoefficient γ is set at γ=¼, m=256.

FIG. 20 is a schematic figure showing an intensity level distribution ofan image formed by the color-modulation light valve.

For the respective areas in the resized image of FIG. 18, in the casecalculating the intensity levels n on the corresponding pixels of thecolor-modulation light valve by use of the gamma characteristicexpression of FIG. 19, at first the intensity level n on the sun isgiven as “256”. However, this value is beyond the number of levels “255”of the color-modulation light valve, it is set to the maximum value“255” as shown in FIG. 20. Meanwhile, the intensity levels n on the skyare respectively given as “179” (left), “209” (upper center), “231”(lower center) and “183” (right). The intensity level n on the cloud is“134” while the intensity levels n on the sea are respectively “183”(left), “241” (center) and “187” (right). The intensity level n on theland is given as “200” while the intensity level n on the snowball isgiven as “0”.

Due to this, the light intensity level on an image formed by thecolor-modulation light valve can be reproduced precisely as compared tothe case with a setting of the gamma coefficient γ at a negative valueor a value greater than ¼.

Incidentally, in the above exemplary embodiment, because theintensity-modulation light valve was constituted by one liquid-crystallight valve 30, one control value library table 400 was prepared todecide a control value of each pixel of the intensity-modulation lightvalve depending upon the control-value library table 400. However, thisis not limitative, i.e. control-value library tables 400R, 400G, 400Bmay be prepared based on RGB three primary colors, to decide a controlvalue of each pixel of the intensity-modulation light valve dependingupon the control-value library tables 400R, 400G, 400B. Because theintensity-modulation light valve is to modulate the intensity of lightover the entire wavelength region, the control-value library table 400is registered with light transmissivities at representative wavelengths.However, RGB three primary colors not necessarily have respectivewavelengths not fallen under the transmissivities registered.

For this reason, for the intensity-modulation light valve, measurementis made for transmissivities corresponding to the control values basedon RGB three primary colors, to thereby configure control-value librarytables 400R-400B. Then, decided is a transmissivity T1 of each pixel ofthe intensity-modulation light valves based on RGB three primary colors,to search through the control-value library table 400R for atransmissivity most approximate to the transmissivity T1 calculated asto R. Thus, read out is a control value corresponding to thetransmissivity found out by the search. Similarly, control valuesconcerned are read out of the control-value library tables 400G, 400B onthe basis of the transmissivity T1 calculated as to G and thetransmissivity T1 calculated as to B. Then, calculated is a mean value,etc. of the control values read out as to a same pixel of theintensity-modulation light valve, as a control value of the relevantpixel.

Due to this, the control value of each pixel of the intensity-modulationlight valve is given as a comparatively suited value for thetransmissivity on RGB three primary colors at the pixel ofcolor-modulation light valve overlapping, on the optical path, with thatpixel. Thus, it is possible to further reduce the possibility ofdeteriorated image quality.

Meanwhile, in the above exemplary embodiment, the color-modulation lightvalve was structured as a light-modulation element decisive of theresolution of display. However, this is not limitative, i.e. theintensity-modulation light valve can be structured as a light-modulationelement decisive of a resolution of display. In this case, afterdeciding a transmissivity T1 of each pixel of the color-modulation lightvalve (transmissivity is given T1 for the light-modulation elementdecided earlier), decided is a transmissivity T2 of each pixel of theintensity-modulation light valve (transmissivity is given T2 for thelight-modulation element decided later). Meanwhile, similarly to theabove, control-value library tables 400R-400B can be prepared based onRGB three primary colors, to decide a control value of each pixel of theintensity-modulation light valve depending upon the control-valuelibrary tables 400R-400B.

Specifically, the transmissivity T2 of each pixel of theintensity-modulation light valve is decided based on RGB three primarycolors. Search is made through the control-value library table 400R fora transmissivity most approximate to the transmissivity T2 calculated asto R, to read out a control value corresponding to the transmissivityfound out by the search. Similarly, a control value concerned is readout of the control-value library tables 400G, 400B, on the basis of thetransmissivity T2 calculated as to G and the transmissivity T2calculated as to B. Then, calculated is a mean value, etc. of thecontrol values read out as to a same pixel of the intensity-modulationlight valve as a control value of that pixel.

Due to this, because the control value of each pixel of theintensity-modulation light valve is given as a comparatively suitablevalue for the transmissivity based on RGB three primary colors at thepixel of color-modulation light valve overlapping, on the optical path,with that pixel. Thus, it is possible to further reduce the possibilityof deteriorated image quality.

Meanwhile, in the above exemplary embodiment, the projection displayapparatus 100 had the intensity-modulation light valve structured by oneliquid-crystal light valve 30. However, this is not limitative, i.e.liquid-crystal light valves 30R, 30G, 30B may be provided respectivelyon the incident sides of the liquid-crystal light valves 40R-40B, asshown in FIG. 21. In this case, the light modulator section for decidinga resolution of display may be any of the liquid-crystal light valves30R-30B and the liquid-crystal light valves 40R-40B.

FIG. 21 is a schematic block diagram showing a hardware constructionwhere a projection display apparatus 100 is structured with anintensity-modulation light valve and color-modulation light valveprovided based on each three colors of RGB.

Due to this, because the intensity level based on RGB three primarycolors can be modulated at two stages independently, it is possible toreduce the possibility of deteriorated image quality.

In this case, the liquid-crystal light valves 30R-30B, 40R-40Bcorrespond to the first light-modulation element of exemplaryembodiments 9, 11 or 29, to the second light-modulation element ofexemplary embodiments 9, 19 or 29, or to the particular wavelengthregioned intensity-modulation element of exemplary embodiments 9, 19 or29.

In the above exemplary embodiment, the projection display apparatus 100was structured by optically directly coupling the intensity modulatorsection 12 and the color modulator section 14 together. However, this isnot limitative, i.e. a relay lens 50 can be structurally providedbetween the intensity modulator section 12 and the color modulatorsection 14, as shown in FIG. 22. In this case, the light modulatorsection to decide a resolution of display may be of any of the intensitymodulator section 12 and the color modulator section 14.

FIG. 22 is a block diagram showing a hardware construction where aprojection display apparatus 100 is structured by providing a relay lens50 between the intensity modulator section 12 and the color modulatorsection 14.

Due to this, because the image by the intensity-modulation light valvecan be accurately transferred onto the color-modulation light valve, theaccuracy of focusing can be enhanced.

In the above exemplary embodiment, the projection display apparatus 100was structured by providing the color modulator section 14 on thelight-exit side of the intensity modulator section 12. However, this isnot limitative, i.e. it can be structured by providing the intensitymodulator section 12 on the light-exit side of the color modulatorsection 14 as shown in FIG. 23. In this case, a relay lens 50 ispreferably provided between the color modulator section 14 and theintensity modulator section 12 in order to enhance the accuracy offocusing. Meanwhile, the light modulator section for deciding aresolution of display may be any of the color modulator section 14 andthe intensity modulator section 12.

FIG. 23 is a schematic block diagram showing a hardware constructionwhere a projection display apparatus 100 is structured by providing anintensity modulator section 12 on the light-exit side of the colormodulator section 14.

In the above structure, the projection display apparatus 100 had thecolor modulator section 14 made up as a three-plated type (scheme forcolor modulation by three liquid-crystal light valves 40R-40B). However,this is not limitative, i.e. it can be structured by making the colormodulator section 14 as a single-plated type (scheme for colormodulation by one liquid-crystal light valve 40) as shown in FIG. 24.The single-plated color-modulation light valve can be structured byproviding a color filter on a liquid-crystal light valve. In this case,a relay lens 50 is preferably provided between the intensity modulatorsection 12 and the color modulator section 14 in order to enhance theaccuracy of focusing. Meanwhile, the light modulator section fordeciding a resolution of display may be any of the intensity modulatorsection 12 and the color modulator section 14.

FIG. 24 is a schematic block diagram showing a hardware constructionwhere a projection display apparatus 100 is structured as asingle-plated type.

In the above exemplary embodiment, the projection display apparatus 100was structured by incorporating the intensity modulator section 12 andthe color modulator section 14. However, this is not limitative, i.e. itcan be structured as a projection display system 300 formed by asingle-plated projection display 310 to modulate the intensity of lightover the entire wavelength region, a flood Fresnel lens 312 forreceiving the projection light from the single-plated projection display310, and a color-modulation panel 314 provided on the light-exit side ofthe Fresnel lens 312 and to modulate the intensity of light based on RGBthree primary colors, as shown in FIG. 25. In this case, the lightmodulator section for deciding a resolution of display may be any of asingle-plated projection display 310 and a color modulator panel 314.

FIG. 25 is a schematic block diagram showing a hardware construction ofa projection display system 300.

In the above exemplary embodiment, the projection display apparatus 100was structured by incorporating the intensity modulator section 12 andthe color modulator section 14. However, this is not limitative, i.e. itcan be structured as a projection display system 300 formed by athree-plated projection display 320 to modulate the intensity of lightbased on RGB three primary colors, a flood Fresnel lens 312 forreceiving the projection light from the three-plated projection display320, and an intensity-modulation panel 324 provided on the light-exitside of the Fresnel lens 312 and to modulate the intensity of light overthe entire wavelength region, as shown in FIG. 26. In this case, thelight modulator section for deciding a resolution of display may be anyof a three-plated projection display 320 and an intensity modulatorpanel 324.

FIG. 26 is a schematic block diagram showing a hardware construction ofa projection display system 300.

In the above exemplary embodiment, the projection display apparatus 100was structured by incorporating the intensity modulator section 12 andthe color modulator section 14. However, this is not limitative, i.e. itcan be structured as a display 400 formed by a backlight 410, anintensity-modulation panel 412 provided on the light-exit side of thebacklight 410 and for modulating the intensity of light over the entirewavelength region, a color-modulation panel 414 provided on thelight-exit side of the intensity-modulation panel 412 and for modulatingthe intensity of light based on RGB three primary colors, as shown inFIG. 27. In this case, the light modulator section for deciding aresolution of display may be any of an intensity-modulation panel 412and a color-modulation panel 414.

FIG. 27 is a schematic block diagram showing a hardware construction ofa display 400.

In this manner, various exemplary variations can be considered as astructure of first light modulator element and second light modulatorelement. Including the structures of FIGS. 1, 21 and 27, the first andsecond light modulator elements have variations in structure that aresummarized as follows. Incidentally, it is assumed that the second lightmodulator element is to decide a resolution of display and has a highresolution.

(1) A single-plated intensity-modulation light valve is used as a secondlight modulator element and a three-plated color-modulation light valveis as a first light modulator element, wherein the second lightmodulator element is provided close to the light source 10 (Structure ofFIGS. 1, 22, 25 and 27). This can reduce manufacturing cost as comparedto the structure (2).

(2) A single-plated intensity-modulation light valve is used as a firstlight modulator element and a three-plated color-modulation light valveis as a second light modulator element, wherein the first lightmodulator element is provided close to the light source 10 (Structure ofFIGS. 1, 22, 25 and 27). This can enhance image quality as compared tothe structure (1).

(3) A three-plated color-modulation light valve is used as a secondlight modulator element and a single-plated intensity-modulation lightvalve is as a first light modulator element, the second light modulatorelement being provided close to the light source 10 (Structure of FIGS.23 and 26). This can enhance image quality as compared to the structure(4).

(4) A three-plated color-modulation light valve is used as a first lightmodulator element and a single-plated intensity-modulation light valveis as a second light modulator element, the first light modulatorelement being provided close to the light source 10 (Structure of FIGS.23 and 26). This can reduce manufacturing cost as compared to thestructure (3).

(5) A three-plated color-modulation light valve is used as a secondlight modulator element and a three-plated color-modulation light valveis as a first light modulator element, the second light modulatorelement being provided close to the light source 10 (Structure of FIG.21). This can enhance image quality as compared to the structure (2) or(3).

(6) A three-plated color-modulation light valve is used as a first lightmodulator element and a three-plated color-modulation light valve is asa second light modulator element, the first light modulator elementbeing provided close to the light source 10 (Structure of FIG. 21). Thiscan enhance image quality as compared to the structure (2) or (3).

(7) A single-plated intensity-modulation light valve is used as a secondlight modulator element and a single-plated color-modulation light valveis as a first light modulator element, the second light modulatorelement being provided close to the light source 10 (Structure of FIG.24). This can reduce manufacturing cost as compared to the structure(8).

(8) A single-plated intensity-modulation light valve is used as a firstlight modulator element and a single-plated color-modulation light valveis as a second light modulator element, the first light modulatorelement being provided close to the light source 10 (Structure of FIG.24). This can enhance image quality as compared to the structure (7).

(9) A single-plated color-modulation light valve is used as a secondlight modulator element and a single-plated intensity-modulation lightvalve is as a first light modulator element, the second light modulatorelement being provided close to the light source 10. This can enhanceimage quality as compared to the structure (10).

(10) A single-plated color-modulation light valve is used as a firstlight modulator element and a single-plated intensity-modulation lightvalve is as a second light modulator element, the first light modulatorelement being provided close to the light source 10. This can reducemanufacturing cost as compared to the structure (9).

(11) A single-plated color-modulation light valve is used as a secondlight modulator element and a three-plated color-modulation light valveis as a first light modulator element, the second light modulatorelement being provided close to the light source 10. This can reducemanufacturing cost as compared to the structure (12).

(12) A single-plated color-modulation light valve is used as a firstlight modulator element and a three-plated color-modulation light valveis as a second light modulator element, the first light modulatorelement being provided close to the light source 10. This can enhanceimage quality as compared to the structure (11).

(13) A three-plated color-modulation light valve is used as a secondlight modulator element and a single-plated color-modulation light valveis as a first light modulator element, the second light modulatorelement being provided close to the light source 10. This can enhanceimage quality as compared to the structure (14).

(14) A three-plated color-modulation light valve is used as a firstlight modulator element and a single-plated color-modulation light valveis as a second light modulator element, the first light modulatorelement being provided close to the light source 10. This can reducemanufacturing cost as compared to the structure (13).

(15) A single-plated color-modulation light valve is used as a secondlight modulator element and a single-plated color-modulation light valveis as a first light modulator element, the second light modulatorelement being provided close to the light source 10. This can enhanceimage quality as compared to the structure (9).

(16) A single-plated color-modulation light valve is used as a firstlight modulator element and a single-plated color-modulation light valveis as a second light modulator element, the first light modulatorelement being provided close to the light source 10. This can enhanceimage quality as compared to the structure (9).

(17) A single-plated intensity-modulation light valve is used as asecond light modulator element and a single-plated intensity-modulationlight valve is as a first light modulator element, the second lightmodulator element being provided close to the light source 10. This canreduce manufacturing cost as compared to the structure (10).

(18) A single-plated intensity-modulation light valve is used as a firstlight modulator element and a single-plated intensity-modulation lightvalve is as a second light modulator element, the first light modulatorelement being provided close to the light source 10. This can reducemanufacturing cost as compared to the structure (10).

In the above exemplary embodiment, control values were decided for theintensity-modulation and color-modulation light valves depending uponHDR display data. However, where utilizing the usual RGB image data at 8bits per color, the value 0-255 of the usual RGB image data is not anintensity physical quantity but a relative value of 0-255. Consequently,in order for the display apparatus of exemplary embodiments of theinvention to make a display depending upon the usual RGB image data,there is a need to decide a physical intensity level Rp for display or atransmissivity Tp of the display overall, from the usual RGB image.

FIG. 28 is a figure showing a data structure of an input-value librarytable 440.

For the purpose, the use of the input-value library table 440 of FIG. 28enables conversion of an input value 0-255 of the usual RGB image into aphysical transmissivity Tp. Furthermore, by the setting manner oftransmissivity Tp in the table, display appearance (intensity levelcharacteristic) can be easily changed for the usual RGB image. Thetransmissivity Tp in the table is Tp of the foregoing equation (2).After this value is decided, the similar processing to the aboveexemplary embodiment decides the transmissivities T1, T2 of a pluralityof light modulator elements thus enabling display.

FIG. 29 is a figure showing a data structure of the input-value librarytable 460.

The input-value library table 460 of FIG. 29 uses intensity level Rp inplace of transmissivity Tp. The intensity level Rp of this table is theRp of the foregoing equation (1). Accordingly, after this value isdecided, the similar processing to the above exemplary embodimentdecides the transmissivities T1, T2 of a plurality of light modulatorelements thus enabling display.

In the above exemplary embodiment, for each pixel of thecolor-modulation light valve, calculated was a weighted mean value ofthe transmissivities T1 decided on the pixel of intensity-modulationlight valve overlapping, on the optical path, with that pixel so that atransmissivity T2 of that pixel can be calculated on the basis of themean value. However, this is not limitative, i.e. for each pixel of thecolor-modulation light valve, on the basis of a control value decided ona pixel of intensity-color light valve overlapping, on the optical axis,with that pixel, a transmissivity T1 _(table) corresponding to thecontrol value can be read out of the control-value library table 400whereby a weighted mean value of the read-out transmissivities T1_(table) is calculated, based on which mean value a transmissivity T2 atthe pixel is calculated.

In the exemplary above embodiment, calculated was a mean value, etc. ofthe transmissivities T1′ calculated based on RGB three primary colors,as T1′ of that pixel. However, this is not limitative, thetransmissivity T1′ can be calculated based on RGB three colors so that,at step S14, a mean value, etc. of the transmissivities T1 calculatedbased on RGB three primary colors on the same pixel can be calculated asT1 of that pixel.

In the above exemplary embodiment, for each pixel of thecolor-modulation light valve, calculated was a weighted mean value ofthe transmissivities T1 decided on the pixel of intensity-modulationlight valve overlapping, on the optical path, with that pixel, tocalculate a transmissivity T2 of that pixel depending upon the meanvalue. However, this is not limitative, i.e. for each pixel of thecolor-modulation light valve, calculated can be a maximum value, aminimum value or a mean value of the transmissivities T1 determined onthe pixel of the intensity-modulation light valve overlapping, on theoptical path, with that pixel, to calculate a transmissivity T2 of thatpixel depending upon the calculated values.

In the above exemplary embodiment, the intensity of light was modulatedat two stages by use of the intensity-modulation and color-modulationlight valves. However, this is not limitative, i.e. the intensity oflight can be modulated at two stages by use of two sets ofintensity-modulation light valves.

In the above exemplary embodiment, the liquid-crystal light valves 30,40R-40B were structured by active-matrix liquid-crystal displays.However, this is not limitative, i.e. the liquid-crystal light valves30, 40R-40B can be structured by using passive-matrix liquid-crystaldisplays and segment liquid-crystal displays. The active-matrixliquid-crystal display has a merit that accurate intensity display ispossible while the passive-matrix liquid-crystal display and segmentliquid-crystal display have an advantage that manufacturing is possibleat low cost.

In the above exemplary embodiment, the projection display apparatus 100was structured by providing a transmission light modulator element.However, this is not limitative, i.e. the intensity-modulation lightvalve or the color-modulation light valve can be structured by areflective light modulator element of DMD (digital micromirror device)or the like. In this case, reflectivity is decided depending upon HDRdisplay data.

In the above exemplary embodiment, used was the light modulator elementsmall in pixel count and intensity levels in order to simplifyexplanation. However, where using a light modulator element great inpixel count and intensity levels, processing is possible similarly tothe above exemplary embodiment.

In the above exemplary embodiment, setting was with gain G=1.0 in orderto simplify explanation. However, gain G=1.0 is not applicable forcertain hardware configurations. Meanwhile, when considering actualcalculation cost, the control-value library table is preferablyregistered with control values and transmissivities in the formincluding the effect of gain G.

In the above exemplary embodiment, explanation was made on the case toexecute the control program previously stored in the ROM 72 uponexecuting the process shown in the flowchart of FIG. 5. However, this isnot limitative, i.e. out of the storage medium storing a program showingthose procedures, the program may be executed by being read out to theRAM 74.

Here, storage medium is a semiconductor storage medium such as a RAM orROM, a magnetic storage medium such as an FD or an HD, anoptical-reading-schemed storage medium such as a CD, a CDV, an LD or aDVD or magnetic-storing-type/optical-reading-schemed storage medium suchas an MD, including any of storage mediums provided that it can be readby a computer regardless of the reading method of electronic, magnetic,optical or the like.

The above exemplary embodiment applied the light propagationcharacteristic control apparatus, optical display, light propagationcharacteristic control program, optical display control program, lightpropagation characteristic control method and optical display controlmethod of exemplary embodiments of the invention to the projectiondisplay apparatus 100, as shown in FIG. 1. However, this is notlimitative, i.e. application is possible to other cases within the scopenot departing from the gist of exemplary embodiments of the presentinvention.

1. A light propagation characteristic control apparatus to be applied toan optical system to modulate light from a light source through a firstlight modulator element having a plurality of pixels capable ofindependently controlling light propagation characteristics and a secondlight modulator element having a plurality of pixels capable ofindependently controlling light propagation characteristics, theapparatus comprising: a light propagation characteristic tentativedeciding device to tentatively decide a light propagation characteristicof each pixel of the second light modulator element depending upondisplay data; and a first light propagation characteristic decidingdevice to decide a light propagation characteristic of each pixel of thefirst light modulator element depending upon a light propagationcharacteristic tentatively decided by the light propagationcharacteristic tentative deciding device and the display data; the lightpropagation characteristic tentative deciding device being allowed totentatively decide a light propagation characteristic of each pixel ofthe second light modulator element by use of a gamma characteristicexpression to calculate an intensity level of light to be modulatedthrough the first and second light modulator elements depending upon anintensity level of light to be modulated through the second lightmodulator element and a gamma coefficient.
 2. An optical displayapparatus, comprising: a light source, a first light modulator elementhaving a plurality of pixels capable of independently controlling lightpropagation characteristics and a second light modulator element havinga plurality of pixels capable of independently controlling lightpropagation characteristics, to thereby modulate light from the lightsource through the first and second light modulator elements and displayan image; a light propagation characteristic tentative deciding deviceto tentatively decide a light propagation characteristic of each pixelof the second light modulator element depending upon display data; afirst light propagation characteristic deciding device to decide a lightpropagation characteristic of each pixel of the first light modulatorelement depending upon the light propagation characteristic tentativelydecided by the light propagation characteristic tentative decidingdevice and the display data; a first control value deciding device todecide a control value of each pixel of the first light modulatorelement depending upon the light propagation characteristic decided bythe first light propagation characteristic deciding device; a secondlight propagation characteristic deciding device to decide a lightpropagation characteristic of each pixel of the second light modulatorelement depending upon the light propagation characteristic decided bythe first light propagation characteristic deciding device and thedisplay data; and a second control value deciding device to decide acontrol value of each pixel of the second light modulator elementdepending upon the light propagation characteristic decided by thesecond light propagation characteristic deciding device; the lightpropagation characteristic tentative deciding device being allowed totentatively decide a light propagation characteristic of each pixel ofthe second light modulator element by use of a gamma characteristicexpression to calculate an intensity level of light to be modulatedthrough the first and second light modulator elements depending upon anintensity level of light to be modulated through the second lightmodulator element and a gamma coefficient.
 3. The optical displayapparatus according to claim 2, the light propagation characteristictentative deciding device calculating the intensity level n with use ofthe gamma characteristic expression Rp=Rmax×(n/m)^(γ), Rp being anintensity level of a pixel p in the display data, Rmax being a maximumvalue of intensity level in the display data, n being an intensity levelof a pixel of the second light modulator element corresponding to thepixel p, m being a coefficient in accordance with the number of levelsof the second light modulator element, and γ being a gamma coefficient,and tentatively deciding a light propagation characteristic of the pixelof the second light modulator element corresponding to the pixel p basedon the calculated intensity level n.
 4. The optical display apparatusaccording to claim 3, the coefficient m being set at a value obtained bymultiplying a multiplier greater than 1 to the number of levels of thesecond light modulator element.
 5. The optical display apparatusaccording to claim 3, the gamma coefficient γ being set at 4 or greater.6. The optical display apparatus according to claim 3, the gammacoefficient γ being set at 0 or greater and ¼ or smaller.
 7. The opticaldisplay apparatus according to claim 2, the second light modulatorelement being a light modulator element decisive of a resolution ofdisplay.
 8. The optical display apparatus according to claim 2, one ofthe first and second light modulator elements being aparticular-wavelength-regioned intensity modulator element to modulatean intensity of light in a particular wavelength region for a pluralityof different particular wavelength regions of a wavelength region oflight, the other of the first and second light modulator elements beingan entire-wavelength-regioned modulator element to modulate an intensityof light over the entire wavelength region.
 9. The optical displayapparatus according to claim 2, the first and second light modulatorelements being particular-wavelength-regioned intensity modulatorelements to modulate an intensity of light in a particular wavelengthregion for a plurality of different particular wavelength regions of awavelength region of light.
 10. The optical display apparatus accordingto claim 2, the second light modulator element having a higherresolution than the first light modulator element.
 11. A lightpropagation characteristic control program for use with a computer to beapplied to an optical system to modulate light from a light sourcethrough a first light modulator element having a plurality of pixelscapable of independently controlling light propagation characteristicsand a second light modulator element having a plurality of pixelscapable of independently controlling light propagation characteristics,the program comprising: a light propagation characteristic tentativedeciding program for tentatively deciding a light propagationcharacteristic of each pixel of the second light modulator elementdepending upon display data; and a first light propagationcharacteristic deciding program for deciding a light propagationcharacteristic of each pixel of the first light modulator elementdepending upon a light propagation characteristic tentatively decided bythe light propagation characteristic tentative deciding program and thedisplay data; the light propagation characteristic tentative decidingprogram being allowed to tentatively decide a light propagationcharacteristic of each pixel of the second light modulator element byuse of a gamma characteristic expression to calculate an intensity levelof light to be modulated through the first and second light modulatorelements depending upon an intensity level of light to be modulatedthrough the second light modulator element and a gamma coefficient. 12.A light display apparatus control program for use with a computer tocontrol an optical display apparatus having a light source, a firstlight modulator element having a plurality of pixels capable ofindependently controlling light propagation characteristics and a secondlight modulator element having a plurality of pixels capable ofindependently controlling light propagation characteristics, to therebymodulate light from the light source through the first and second lightmodulator elements and display an image, the program comprising: a lightpropagation characteristic tentative deciding program for tentativelydeciding a light propagation characteristic of each pixel of the secondlight modulator element depending upon display data; a first lightpropagation characteristic deciding program for deciding a lightpropagation characteristic of each pixel of the first light modulatorelement depending upon the light propagation characteristic tentativelydecided by the light propagation characteristic tentative decidingprogram and the display data; a first control value deciding program fordeciding a control value of each pixel of the first light modulatorelement depending upon the light propagation characteristic decided bythe first light propagation characteristic deciding program; a secondlight propagation characteristic deciding program for deciding a lightpropagation characteristic of each pixel of the second light modulatorelement depending upon the light propagation characteristic decided bythe first light propagation characteristic deciding program and thedisplay data; and a second control value deciding program for deciding acontrol value of each pixel of the second light modulator elementdepending upon the light propagation characteristic decided by thesecond light propagation characteristic deciding program; the lightpropagation characteristic tentative deciding program being allowed totentatively decide a light propagation characteristic of each pixel ofthe second light modulator element by use of a gamma characteristicexpression to calculate an intensity level of light to be modulatedthrough the first and second light modulator elements depending upon anintensity level of light to be modulated through the second lightmodulator element and a gamma coefficient.
 13. A light propagationcharacteristic control method to be applied to an optical system formodulating light from a light source through a first light modulatorelement having a plurality of pixels capable of independentlycontrolling light propagation characteristics and a second lightmodulator element having a plurality of pixels capable of independentlycontrolling light propagation characteristics, the method comprising:tentatively deciding a light propagation characteristic of each pixel ofthe second light modulator element depending upon display data; anddeciding a light propagation characteristic of each pixel of the firstlight modulator element depending upon a light propagationcharacteristic tentatively decided by the light propagationcharacteristic tentative deciding and the display data; the lightpropagation characteristic tentative deciding being allowed totentatively decide a light propagation characteristic of each pixel ofthe second light modulator element by use of a gamma characteristicexpression to calculate an intensity level of light to be modulatedthrough the first and second light modulator elements depending upon anintensity level of light to be modulated through the second lightmodulator element and a gamma coefficient.
 14. The optical displayapparatus control method to control an optical display apparatus havinga light source, a first light modulator element having a plurality ofpixels capable of independently controlling light propagationcharacteristics and a second light modulator element having a pluralityof pixels capable of independently controlling light propagationcharacteristics, to thereby modulate light from the light source throughthe first and second light modulator elements and display an image, themethod comprising: tentatively deciding a light propagationcharacteristic of each pixel of the second light modulator elementdepending upon display data; deciding a light propagation characteristicof each pixel of the first light modulator element depending upon thelight propagation characteristic tentatively decided by the lightpropagation characteristic tentative deciding and the display data;deciding a control value of each pixel of the first light modulatorelement depending upon the light propagation characteristic decided bythe first light propagation characteristic deciding; deciding a lightpropagation characteristic of each pixel of the second light modulatorelement depending upon the light propagation characteristic decided bythe first light propagation characteristic deciding and the displaydata; and deciding a control value of each pixel of the second lightmodulator element depending upon the light propagation characteristicdecided by the second light propagation characteristic deciding; thelight propagation characteristic tentative deciding being allowed totentatively decide a light propagation characteristic of each pixel ofthe second light modulator element by use of a gamma characteristicexpression to calculate an intensity level of light to be modulatedthrough the first and second light modulator elements depending upon anintensity level of light to be modulated through the second lightmodulator element and a gamma coefficient.